UNIVERSITY    OF    CALIFORNIA 

COLLEGE    OF    AGRICULTURE 

AGRICULTURAL    EXPERIMENT   STATION 

BERKELEY,    CALIFORNIA 

CIRCULAR  No.  284 
April,  1925 

THE  ALMOND  IN  CALIFORNIA 

By  R.  H.  TAYLOR  and  G.  L.  PHILP 


INTRODUCTION 

The  almond  (Prunus  communis)  is  supposed  to  be  native  to  the 
countries  around  the  Mediterranean.  It  is  related  to  the  peach  which 
it  resembles  in  manner  of  growth  and  character  of  blossoms  and 
leaves.  The  wood,  however,  is  much  harder  and  the  tree  lives  longer 
under  equally  favorable  conditions.  The  fruit  Jias  a  thin,  leathery 
pericarp  or  hull,  which  corresponds  to  the  thick,  fleshy  portion  of  the 
peach,  and  which  splits  upon  ripening  and  generally  opens  when 
dry,  exposing  the  nut  inside. 


ALMOND  PRODUCTION  AND  DISTRICTS 

The  production  of  almonds  in  the  United  States  is  confined  almost 
entirely  to  California,  where  over  99  per  cent  of  the  crop  is  raised. 
With  the  1915  crop  the  production  entered  upon  what  appears  to  be 
a  long  prospective  increase.  The  large  acreage  of  almonds  set  out 
in  the  past  few  years  is  the  result  of  greatly  improved  market  con- 
ditions which  are  due  to  the  successful  work  of  the  California  Almond 
Growers'  Exchange.  According  to  recent  figures,1  there  are  now 
approximately  100,000  acres  of  bearing  and  non-bearing  trees  and 
large  acreages  are  still  being  planted. 

Table  1  gives,  by  counties,  the  comparison  of  the  number  of  acres 
in  bearing  in  1909,  with  the  bearing  and  non-bearing  acreages  for 
1923. 


*  This  circular  is  a  revision,  by  the  junior  author,  of  California  Agr.  Exp.  Sta. 
Bull.  297,  by  R.  H.  Taylor. 

i  California  Crop  Eeport,  Calif.  State  Dept.  Agr.,  Special  Publication  43,  p.  21, 
1924. 


2  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

TABLE   1 

Comparison  of  Bearing  Acres  of  Almonds  in  the  Various  Counties  in  19092 
with  the  Bearing  and  Non-Bearing  Acres  in  1923 


Bearing  acres, 

Bearing  acres, 

Non-bearing  acres, 

County 

1909 

1923 

1923 

Alameda 

246 

400 

Amador 

14 

7 

Butte 

1051 

5133 

572 

Calaveras 

23 

7 

Colusa 

201 

3200 

5900 

Contra  Costa 

2613 

2500 

522 

Fresno 

84 

167 

Glenn 

359 

2703 

217 

Kern 

170 

80 

Kings 

15 

5 

Lake 

103 

300 

346 

Los  Angeles 

962 

1062 

166 

Madera 

141 

108 

Marin 

10 

7 

Mendocino 

11 

Merced 

214 

3321 

599 

Monterey 

2400 

150 

Napa 

234 

20 

23 

Placer 

144 

389 

20 

Riverside 

272 

1432 

53 

Sacramento 

829 

2376 

551 

San  Benito 

87 

130 

8 

331 

26 

San  Bernardino 

7 

San  Diego 

185 

San  Joaquin 

1212 

5592 

481 

San  Luis  Obispo 

116 

8489 

21,987 

San  Mateo 

323 

6 

2 

200 

60 

4 

Santa  Barbara 

1 

Santa  Clara 

160 

Shasta 

Siskiyou 

3 

3 

Solano 

1228 

1776 

126 

Sonoma 

25 

15 

Stanislaus 

421 

4170 

1080 

Sutter 

769 

2090 

32 

Tehama 

411 

662 

24 

Tulare 

832 
731 

46 

Ventura 

57 

Yolo 

1862 

5554 

2000 

Yuba 

39 

290 

60 

All  other  counties 

827 

The  State 

14,541 

56,646 

35,794* 

*  Estimated  acreage  planted  in  state,  1923,  5,921  not  included. 


2  Figures  for 
144,  1919. 


1909  from  Calif.  State  Board  of  Hort.,  Mo.  Bull.,  vol.  8,  no.  4, 


Circ.  284] 


THE  ALMOND  IN   CALIFORNIA 


It  is  interesting  to  note  that  the  bearing  acreage  is  confined  mainly 
to  the  upper  part  of  the  great  interior  valley,  extending  from  Tehama 
County  on  the  north  to  Merced  County  on  the  south.  The  largest 
proportion  of  the  non-bearing  acreage  is  confined  to  San  Luis  Obispo 
County,  where  the  almond  is  being  extensively  planted.  Figure  1 
shows  the  location  of  the  almond  plantings. 


.S   (  S    K    I    YOU 


MODOC 


FT 


S   H  A   S  T  A  I 


l        '  T     E     H   _A 


^      t 
*1 


•\l 


ALMONDS 
ACREAGE   III  CALIFORNIA 


EACH  DOT  =  500  ACHES. 
Leading  Counties  by  acres: 
San  Luis  Obispo  30,476 

Colusa  9,100 

Yolo  7,544 

San  Joaquin  6,073 

Butte  5,705 

THE  STATB   (Bearing)  56,646 

(Non-bearing)     35,794 


*XV 


SJPSSX&1  f  \   °    \     From  California  Crop 

•^llV'o°tUMNEA^     *\     Report  -  1923 


N 


-V 


V 


V 


\ 


Leading  Counties 

Based  on  Average  Pro  due- 
tion 


nta  barbaraI   *V    \ 


SAN       B  ERNARO  I  N  0 


1st.  Butte 

2nd.   Yolo 

3rd. (San  Joaquin 

(San  Luis  Obispo 
8th.  Colusa 

From  California  Crop  Reporting  Service 
June  3,  1924. 


IMPERIAL 


Fig.  1. — Outline  map  of  California  showing  the  almond  acreage  by  counties. 
Each  dot  represents  500  acres.  The  leading  counties  based  on  average  production 
are  also  listed. 

While  California  produces  practically  all  the  almonds  grown  in 
the  United  States,  there  are  millions  of  pounds  imported  into  this 
country  every  year.  Table  2  gives  the  quantities  of  almonds  brought 
into  the  United  States  during  the  years  1917  to  1923,  inclusive : 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

TABLE  2 
Almond  Imports.    Crops  of  1917  to  1923a 


Imports  for 

Crops  of 

Pounds 
Unshelled 

Pounds 
Shelled 

Total  pounds 

1917-18 

1917 
1918 
1919 
1920 
1921 
1922 

4,278,990 
6,733,512 
7,355,894 
6,622,340 
4,637,002 
4,719,348 

19,561,155 
23,594,915 
26,326,245 
13,816,044 
26,705,621 
22,973,337 

23,840,145 
30,328,427 

1918-19 

1919-20 

33,682,139 

1920-21 

20,438,384 

1921-22 

31,342,623 

1922-23 

27,692,685 

Since  the  cost  of  producing  almonds  in  Europe  and  of  transport- 
ing them  to  the  Atlantic  seaboard  is  low,  the  Californian  grower  must 
become  thoroughly  familiar  with  the  most  economical  methods  of 
production  and  marketing. 


HABITS 

The  almond  is  the  first  of  the  deciduous  fruit  trees  to  start  growth 
and  come  into  bloom  in  the  spring,  and  is  normally  the  last  one  to 
shed  its  leaves  in  the  fall.  In  other  words,  it  has  a  very  short  period 
of  rest.  When  the  trees  are  forced  into  premature  dormancy  by  mites 
or  lack  of  moisture,  they  reach  the  end  of  their  normal  rest  period 
before  the  winter  season  is  over.  Then  the  first  warm  weather  in 
spring  will  bring  the  trees  into  bloom.  In  some  cases  where  moisture 
and  temperature  conditions  are  favorable  late  in  the  fall,  they  may 
actually  blossom  before  the  winter  season  begins.  In  young  trees 
that  have  become  dormant  unusually  early,  the  rest  period  may  term- 
inate and  the  tips  of  the  branches  resume  growth  and  continue  slowly 
to  develop  new  leaves  at  the  terminals  throughout  the  winter.  Trees 
which  have  been  kept  growing  until  the  leaves  have  been  forced  to 
fall  by  the  cold  weather  and  frosts  of  winter,  do  not  usually  blossom 
so  early  in  the  spring. 

Young  trees  blossom  somewhat  later  than  older  ones,  and  buds  on 
sucker  growth  blossom  later  than  those  on  the  more  mature  portions 
of  the  same  tree.  The  difference  may  amount  to  three  or  four  days 
or  almost  a  week.  Well  grown  trees  carry  large  numbers  of  blossoms 
over  the  entire  tree. 


3  Figures  from  the  California  Almond  Growers '  Exchange. 


ClRC.  284]  THE  almond  IN  CALIFORNIA  5 

The  wood  of  the  almond  is  very  hard  and  strong,  enabling  the 
tree  to  bear  the  weight  of  heavy  crops  where  proper  pruning  has  been 
given  during  the  first  years  of  growth.  As  with  other  fruit  trees, 
the  almond  is  subject  to  heart-rot  and  needs  care  to  prevent  the  check- 
ing and  cracking  of  large  wounds  and  consequent  infection  with  decay 
organisms.  The  hardness  of  the  wood  makes  it  excellent  fuel,  and 
when  old  orchards  are  being  dug  up,  the  returns  from  the  sale  of 
wood  often  more  than  pay  for  the  expense  of  digging  and  cutting  up 
the  trees  and  burning  the  brush. 

The  nuts  are  of  two  general  classes — sweet  and  bitter.  The  former 
is  primarily  the  almond  of  commerce,  though  the  latter  is  used  largely 
in  the  manufacture  of  almond  oil  and  almond  flavoring,  as  well  as 
in  the  manufacture  of  prussic  acid.  The  bitter  almond  is  also  much 
used  in  nurseries  as  a  rootstock  upon  which  to  bud  the  almond  and 
some  other  fruits. 


FACTORS  LIMITING  PRODUCTION 

While  the  almond  is  in  many  ways  an  easy  tree  to  grow  it  is 
rather  particular  in  certain  pollination,  climatic,  and  soil  require- 
ments. 

POLLINATION 

Tufts  and  Philp4  found  that  all  of  the  varieties  of  almonds  they 
tested  are  self-sterile.  This  list  includes  the  Big  White  Flat,  Califor- 
nia, Drake,  Eureka,  Golden  State,  Harriott,  I.  X.  L.,  Jordan,  King, 
Klondike,  Languedoc,  Lewelling,  Ne  Plus  Ultra,  Nonpareil,  Peerless, 
Princess,  Reams,  Sellers,  Silver  Shell,  and  Texas. 

In  addition  certain  almond  varieties  are  inter-sterile.  For 
example,  the  I.  X.  L.  and  the  Nonpareil  proved  practically  inter- 
sterile.  The  Languedoc  and  the  Texas  are  inter-sterile  as  shown  by 
two  seasons'  work. 

In  order  to  insure  cross-pollination  it  is  necessary  therefore  to 
interplant  varieties  which  not  only  are  inter-fertile  but  blossom  at 
about  the  same  time.  The  accompanying  chart  (fig.  2)  gives  the 
average  blooming  periods  of  certain  almond  varieties.  The  date  of 
bloom  is  of  course  dependent  upon  many  factors,  such  as  soil,  season, 
and  location. 


4  Tufts,  W.  P.,  and  Philp,  G.  L.,  California  Agr.  Exp.  Sta.,  Bull.  346,  1922. 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


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THE  ALMOND  IN   CALIFORNIA 


Figure  3  gives  the  period  of  effective  bloom  of  certain  almond 
varieties  for  the  year  1917  growing  under  the  same  conditions. 
Satisfactory  pollinizers  for  various  varieties  are  listed  below : 

1.  For  California — Nonpareil  and  Drake. 

2.  For  Drake — California,  Ne  Plus  Ultra,  Nonpareil,  and  Texas. 

3.  For  Eureka — Nonpareil. 

4.  For  Harriott — Ne  Plus  Ultra. 

5.  For  I.  X.  L.— Ne  Plus  Ultra. 

6.  For  Languedoc — Drake. 


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Fig.  3. — The  effective  blooming  period  of  certain  almond  varieties  during  the 
season  of  1917.  The  dates  in  this  table  cover  the  time  each  variety  was  in  con- 
spicuous bloom  and  therefore  of  maximum  attraction  to  insects.  From  Bull.  346, 
Calif.  Exp.  Sta. 


7.  For  Ne  Plus  Ultra — California,  I.  X.  L.,  Jordan,  and  Non- 
pareil. 

8.  For  Nonpareil — California,  Drake,  Jordan,  Ne  Plus  Ultra, 
Peerless,  and  Texas. 

9.  For  Beams — Texas. 

10.  For  Texas — Drake  and  Nonpareil. 

There  are  a  few  other  suggestions  concerning  pollination  of 
almonds  which  are  listed  below : 

(a)  Pollinizing  agencies,  such  as  the  honey  bee,  are  necessary  to 
set  a  good  crop  of  nuts. 

(6)  One  colony  oi;  honey  bees  to  each  acre  of  orchard  insures  a 
proper  transmission  of  pollen. 


8  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

(c)  To  facilitate  cross-pollination  and  convenience  in  harvesting, 
it  is  best  to  plant  two,  three,  or  four  rows  of  one  kind  and  then  a 
similar  number  of  the  other  variety.  When  a  smaller  number  of  the 
pollinizer  is  desired,  two  rows  to  every  four  rows  of  the  standard 
variety  can  be  planted. 

(d)  When  it  is  desired  to  reduce  the  number  of  pollinizing  trees 
to  the  minimum,  one  tree  in  twenty-five  is  perhaps  sufficient,  although 
at  least  one  tree  in  eight  is  strongly  recommended.  This  can  be  done 
by  planting  the  pollinizing  variety  as  every  third  tree  in  every  third 
row.  Such  an  arrangement,  however,  makes  it  difficult  to  avoid 
mixing  varieties  in  harvesting. 

(e)  Planting  several  varieties  also  assists  greatly  in  lengthening 
the  harvest  season  and  thus  enabling  an  individual  to  handle  larger 
crops  with  fewer  men  and  less  equipment.  For  example,  the  four 
best  varieties,  the  Nonpareil,  I.  X.  L.,  Ne  Plus  Ultra,  and  Drake,  ripen 
in  the  order  named :  the  Nonpareil  ripening  about  two  weeks  before 
the  I.  X.  L.,  the  Ne  Plus  Ultra  about  a  week  after  the  I.  X.  L.,  and 
the  Drake  about  two  weeks  after,  the  Ne  Plus  Ultra. 

CLIMATE 

Heat. — Where  the  conditions  of  soil  and  moisture  are  favorable, 
the  almond  will  endure  the  intense  heat  of  the  interior  valleys  and 
even  of  the  Imperial  Valley,  provided  it  is  pruned  properly  to  shade 
the  main  branches  and  prevent  sunburn.  If  trees  are  opened  up 
suddenly  to  the  intense  heat  of  the  summer  sun,  they  are  apt  to  sun- 
burn, but  if  this  opening  up  is  done  gradually,  the  bark  will  become 
inured  to  the  new  conditions  without  danger.  The  nuts  grow  and 
ripen  more  satisfactorily  in  the  greater  heat  of  the  interior  than 
along  the  coast. 

Frost. — The  almond  tree  is  hardy  and  can  endure  without  injury 
fully  as  much  cold  as  the  hardiest  peach.  Trees  are  found  growing 
well  in  Illinois,  Nebraska,  Ohio,  New  York,  and  other  Eastern  states. 
In  very  favorable  seasons  they  may  even  bear  fruit,  though  this 
happens  very  seldom,  because  of  their  habit  of  blooming  before  the 
spring  frosts  are  over.  The  first  Avarm  weather  seems  to  start  the 
trees  into  bloom,  especially  where  the  enforcd  dormant  season  of 
winter  is  very  long. 

While  the  wood  is  relatively  hardy,  the  blossoms  on  the  other  hand, 
are  very  tender.  There  is  a  great  range  in  the  degree  of  frost  which 
causes  injury,  depending  largely  upon  the  condition  of  the  tree 
during  the  time  that  the  fruit-buds  are  forming  and  developing,  as 


CIRC.   284]  THE  ALMoND  IN   CALIFORNIA  9 

well  as  upon  the  duration  and  severity  of  the  frost.  Buds  and 
blossoms  on  trees  which  have  been  forced  into  premature  dormancy, 
either  by  lack  of  moisture  or  by  severe  attacks  of  red  spider,  are  much 
more  susceptible  to  frost  injury  than  those  on  trees  which  have  con- 
tinued growth  late  enough  in  the  fall  to  provide  for  the  proper  devel- 
opment and  maturity  of  the  buds.  After  differentiation  of  fruit-buds 
commences  in  the  summer,  the  almond  leaves  should  remain  on  the 
tree  until  late  into  the  fall  in  order  to  strengthen  and  develop  the 
fruit-buds  and  store  up  elaborated  food  material  for  their  normal 
development  through  the  winter.  Studies  of  almond  buds  gathered 
from  healthy  trees  which  held  their  leaves  until  late  fall  frosts  at 
Davis,  showed  the  first  evidence  of  differentiation  of  fruit  or  flower- 
buds  about  mid- August,  while  the  flower  was  not  completely  developed 
until  early  February  of  the  next  year,  following.  During  the  interven- 
ing time,  development  proceeded  unchecked  through  the  winter  even 
though  the  tree  was  apparently  dormant.  During  the  time  the  crop  is 
ripening  on  the  trees,  little  is  done  toward  storing  food  material  for 
the  buds.  If  the  leaves  turn  yellow  or  drop  soon  after  harvest,  the 
trees  do  not  have  the  opportunity  of  storing  a  sufficient  supply  of 
plant  food  for  their  normal  requirements  and  the  buds  are  insuf- 
ficiently nourished  during  the  winter  period.  The  resulting  buds  are 
weakened,  and  the  indications  are  that  they  are  unable  to  endure 
unfavorable  climatic  conditions  in  the  spring,  such  as  light  frosts, 
continued  cold  weather,  or  sudden  changes  from  warm  to  cold. 

The  most  tender  stage  in  the  blossoming  and  development  of  the 
young  fruit  seems  to  be  immediately  after  the  dropping  of  the  calyx 
lobes  and  when  rapid  growth  begins.  The  blossom  becomes  more  and 
more  tender  as  it  opens.  Blossoms  with  the  petals  exposed  but  not 
yet  opened  have  been  known  to  stand  a  temperature  of  24°  F.,  and 
blossoms  with  petals  beginning  to  fall  have  stood  28°  F.  No  records 
are  available  as  to  the  duration  of  these  temperatures.  In  other  cases, 
blossoms  with  the  petals  falling  have  been  killed  by  temperatures  of  30° 
and  31°  F.  It  must  be  remembered  in  this  connection  that  the  almond 
blooms  earlier  than  other  orchard  fruits  and,  therefore,  is  often  sub- 
jected to  much  more  severe  frosts  than  occur  during  the  blooming 
period  of  the  later  fruits.  The  greatest  injury  is  likely  to  occur  when 
the  frost  follows  one  or  more  days  of  warm  weather.  When  the  mean 
temperature  both  day  and  night  remains  low,  frosts  that  might  other- 
wise kill  the  flowers  or  setting  fruit  do  no  harm.  This  is  what 
occurred  in  February,  1917,  at  the  University  Farm,  when  repeated 
frosts  at  blooming  time  did  no  harm  whatever. 


10  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Freedom  from  frost  and  adequate  air  drainage  are  closely  related. 
The  lands  along  the  lower  foothills  immediately  above  the  floor  of  the 
valleys  and  the  lands  along  the  built  up  banks  of  rivers  are  less 
subject  to  frost  because  the  cold  air  flows  from  them  to  the  lower 
lands  adjacent.  For  this  reason,  the  planting  of  almonds  in  the  lower 
lands  of  the  valleys,  no  matter  how  large  the  valleys  may  be,  should 
be  avoided.  An  exception  may  be  the  locality  which  has  been 
thoroughly  tested  as  to  frost  occurrence  for  a  long  period  of  years 
and  has  proved  to  be  frost  free,  because  of  some  peculiar  situation 
with  favoring  air  currents  or  air  drainage,  such  as  might  exist  near 
a  natural  draw  in  the  hills  where  the  settling  of  the  cold  air  in  some 
portions  of  the  adjacent  valley  might  be  prevented.  Such  locations 
are  generally  confined  to  very  small  areas.  Sometimes  an  opening  or 
draw  in  the  hills  may  serve  as  an  outlet  for  the  drainage  of  much 
colder  air  from  considerably  higher  elevations  beyond,  and  then  the 
danger  from  frost  is  very  greatly  increased.  This  is  very  common 
where  canons  act  as  drains  to  conduct  the  cold  air  from  the  high 
Sierras  to  the  valleys  below. 

Variable  weather  conditions,  especially  as  regards  temperature  in 
the  spring  after  growth  commences,  are  undesirable.  At  this  time 
sudden  changes  of  weather,  even  without  frost,  often  destroy  the 
crop.  However,  it  is  probable  that  most  of  the  dropping  of  fruit 
when  the  size  of  peas  or  larger,  is  due  to  improper  pollination. 

Humidity. — Foggy  or  moist  weather  during  ripening  or  harvest- 
ing promotes  the  growth  of  molds  and  consequent  darkening  of  the 
shells,  which  then  require  much  heavier  bleaching.  It  also  prevents 
the  rapid  and  thorough  drying-out  of  the  kernel,  which  when  moist 
absorbs  sulfur  fumes  and  sometimes  become  rancid  in  less  than  six 
months. 

Much  damp  weather  in  spring  encourages  the  growth  of  "shot- 
hole"  fungus  in  the  blossoms  and  fruit,  often  causing  the  loss  of  a 
considerable  portion  of  the  crop.  The  loss  of  leaf  surface  from  this 
fungus  is  also  sometimes  so  great  as  materially  to  affect  the  vigor  and 
vitality  of  the  tree. 

Rainfall. — The  average  amount  of  rainfall  which  will  maintain  the 
trees  and  enable  them  to  bear  regular  crops  depends  on  its  annual 
variations,  its  distribution  throughout  the  year,  the  time  and  intensity 
of  the  rains,  the  character  of  the  weather  following,  and  the  ability 
of  the  soil  to  receive  and  retain  them.  Ordinarily,  however,  with  the 
above  factors  favorable,  it  is  conceded  that  where  the  winter  rainfall 
averages  sixteen  inches,  almonds  can  generally  be  grown,  although 


ClRC.  284]  THE  ALM0ND  IN  CALIFORNIA  11 

not  always  very  satisfactorily,  without  irrigation,  if  the  orchardist 
exercises  reasonable  care  in  conserving  the  moisture  for  the  use  of 
the  trees.  Where  the  rainfall  is  inadequate,  some  means  of  irrigation 
must  be  found  to  make  up  the  deficit. 

In  some  sections  the  annual  rainfall  varies  greatly  from  year  to 
year.  Often  it  falls  in  such  a  way  that  a  large  proportion  of  it  is 
lost  in  the  surface  run-off.  In  many  places  the  soil  is  so  leachy  that  it 
is  incapable  of  holding  sufficient  water  for  the  use  of  the  trees 
throughout  the  summer,  much  of  the  winter  rainfall  being  lost  in  the 
underground  drainage.  Under  any  of  these  conditions,  forty  inches 
of  rainfall  might  not  be  sufficient. 

Continued  rainy,  damp,  and  cold  weather  at  blooming  time  is  apt 
to  destroy  the  pollen  and  thus  prevent  the  fertilization  without  which 
a  crop  is  impossible.  Such  weather  also  prevents  insects  from  work- 
ing, particularly  bees,  which  are  the  principal  means  of  pollinating 
almonds. 

Soil. — The  almond  is  a  deep-rooting  tree  which  draws  heavily 
upon  the  plant-nourishing  elements  of  the  soil.  In  ripening  the  large 
number  of  fruits  which  it  is  required  to  do,  the  tree  must  draw  upon 
a  considerable  area  of  soil  in  order  to  supply  the  large  amount  of 
mineral  matter  that  is  needed  to  develop  and  mature  the  seeds. 
Analyses  of  almonds  made  by  Colby5  show,  when  compared  with  other 
commonly  grown  fruits  and  nuts,  that  the  almond  tree  leads  in  the 
total  quantity  of  mineral  matters  withdrawn  from  the  soil.  Colby 
states  that  ' '  The  stone  fruits  fall  much  below  the  almond  in  total  ash 
(mineral  matter)  excepting  the  olive,  the  ash  of  which,  however,  is 
largely  silica  (nearly  eight-tenths),  an  ingredient  so  plentifully  dis- 
tributed in  all  soils  that  it  is  of  no  pecuniary  value." 

Hardpan. — Compacted  substrata  in  the  soil,  whether  they  be  hard 
clay  layers  or  cemented  layers  of  silicous,  ferruginous  or  calcareous 
origin,  are  objectionable.  Not  only  do  they  keep  the  roots  from 
foraging  to  a  considerable  depth  as  they  normally  tend  to  do,  but 
they  prevent  proper  drainage  and  aeration  of  the  soil.  If  such 
layers  are  comparatively  thin,  that  is,  not  more  than  one  or  two  feet 
thick  at  the  most,  they  may  be  shattered  with  dynamite  so  as  to  allow 
the  moisture,  air,  and  roots  to  penetrate  to  better  soil  below.  Hard- 
pan,  therefore,  should  be  avoided  when  it  is  too  thick  to  be  broken 
up  or  where  it  is  not  underlaid  by  desirable  soil. 

Humus. — A  plentiful  supply  of  humus  in  the  soil  is  essential.  It 
not  only  improves  the  physical  condition  of  the  soil,  but  assists  drain- 
age and  moisture  retention  and  renders  the  plant  food  available  for 


s  Colby,  Geo.   E.,  California  Agr.  Exp.   Sta.,  Ann.   Kept.,  pp.   142-159,   1898. 


12  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

the  use  of  the  trees  and  for  the  maturing  of  full  crops.  Many 
orchards  are  very  light  producers  because  of  a  deficiency  of  humus 
in  the  soil. 

Drainage. — The  almond  root  is  very  particular  as  to  its  air  and 
moisture  requirements  in  the  soil.  It  suffers  from  standing  water  in 
the  soil  especially  during  the  growing  season.  Exclusion  of  air  by 
excessive  moisture  is  believed  to  be  one  of  the  most  productive  causes 
of  "sour-sap."  If  allowed  to  continue  for  any  considerable  length 
of  time,  such  a  condition  will  cause  the  death  of  many  or  even  of  all 
the  roots  and,  with  them,  the  top. 

Water  Table. — A  factor  which  is  very  commonly  overlooked  in 
connection  with  the  natural  drainage  of  almond  lands  is  the  position 
of  the  water  table  at  different  seasons  of  the  year.  Great  care  must 
be  exercised  to  choose  a  location  where  the  water  table  does  not  rise 
during  the  summer.  This  is  a  very  serious  problem  in  many  irrigation 
sections.  Where  the  Avater  table  during  the  winter  months  is  less  than 
twelve  feet  in  depth,  it  is  desirable  to  have  as  little  fluctuation  as 
possible.  Where  fluctuations  take  place  at  a  greater  depth  than 
twelve  feet,  they  are  not  generally  serious.  The  ideal  condition  is  one 
where  the  water  table  is  highest  in  the  winter  and  quickly  drops,  after 
the  winter  rains  are  over,  to  a  depth  of  from  ten  to  twelve  or  fifteen 
feet,  remaining  at  that  point  during  the  remainder  of  the  growing 
season. 

The  soil  in  addition  to  being  well  drained,  must  be  sufficiently 
retentive  of  moisture  to  supply  the  tree  throughout  a  long,  dry  grow- 
ing season.  If  the  soil  will  not  retain  a  sufficient  amount  of  the  winter 
and  spring  rains,  recourse  must  be  had  to  irrigation  to  supply  the 
deficiency. 

Alkali. — Alkali  lands  are  unsuited  to  almond  culture  and  should 
be  carefully  avoided. 

To  summarize  the  soil  requirements  for  almond  culture :  the  ideal 
almond  soil  is  a  deep  medium  loam,  uniform  in  texture,  or  nearly  so, 
well  drained,  and  yet  retentive  of  moisture  for  the  use  of  the  tree 
during  the  summer.  Fortunately,  some  of  the  best  almond  soils  are 
situated  along  river  banks  where  the  land  is  relatively  high,  and  is, 
therefore,  less  subject  to  frost. 

The  various  requirements  of  growth  and  production  are  those 
mentioned  above.  Often  these  conditions  may  be  approached  in  a 
relatively  shallow  soil.  It  is  essential  to  understand  that  trees,  while 
growing  and  bearing  on  shallow  soils  in  some  localities,  do  so  because 
of  other  exceptionally  favorable  conditions;  either  the  soil  is  unusually 


CIRC.  284]  THE  ALM0ND  IN   CALIFORNIA  13 

well  drained  and  yet  sufficiently  retentive  of  moisture,  or  the  humus 
in  the  soil  is  plentiful  and  the  roots  are  able  to  work  into  the  partially 
decomposed  rock  underlying  it  for  moisture  and  for  some  plant  food. 
In  such  localities  the  trees  may  bear  comparatively  well  because  of 
exceptional  freedom  from  frost  in  the  spring.  They  are  generally 
smaller,  however,  than  those  on  the  deeper,  richer  soils,  and  where 
other  conditions  are  equal,  they  bear  crops  in  proportion  to  their  size. 


PROPAGATION 

Orchard  almond  trees  are  never  grown  from  seed,  which  do  not 
reproduce  the  type,  but  they  are  propagated  by  budding  desirable 
varieties  on  seedling  roots  in  the  manner  commonly  employed  in 
nursery  practice  for  the  peach  and  other  stone  fruits.  The  grower 
should  consider  carefully  what  rootstocks  to  select. 

Rootstocks. — There  is  still  much  to  learn  regarding  the  behavior 
of  the  different  roots  under  varying  conditions  when  used  as  stock 
for  the  almond,  but  sufficient  information  has  already  been  gathered 
to  warrant  certain  recommendations.  A  survey  of  the  California 
nurseries  in  1922  showed  that  72  per  cent  of  the  almonds  were  propa- 
gated on  almond  root  and  28  per  cent  on  peach  root. 

Almond  Root. — Most  almonds  in  this  state  are  on  almond  roots. 
Where  favorable  soil,  moisture,  and  drainage  conditions  exist  the 
almond  root  is  best.  It  will  live  in  comparatively  dry  soils,  but  will 
not  make  a  tree  of  large  size  or  bear  good  crops  if  the  conditions  are 
too  dry. 

Where  irrigation  is  not  available,  and  the  soil  is  deep  and  of 
proper  texture,  sufficient  moisture  may  be  retained  in  most  years  to 
enable  the  tree  to  grow  and  bear  fruit.  When  extra  dry  years  come, 
though  the  almond  root  may  not  enable  the  tree  to  grow  or  produce 
better  than  would  another  kind  of  root,  it  will  carry  the  tree  over  a 
few  dry  seasons  as  well  as  or  better  than  any  other.  Then,  when  suf- 
ficient moisture  does  come,  the  almond  root  is  ready  to  start  the  tree 
off  on  its  normal  course  with  the  least  loss  of  time. 

The  bitter  almond  is  often  recommended  as  being  superior  to  the 
sweet  almond  as  a  stock.  This  has  never  been  proved.  Experiments 
indicate  that  there  is  as  much  variation  among  the  bitter  almond 
seedlings  grown  from  seed  from  different  trees  as  there  is  among 
seedlings  from  sweet  almonds.  Both  are  equally  subject  to  attack  by 
gophers.  There  is  no  reason  therefore  for  preferring  one  to  the  other 
provided  healthy,  vigorous  trees  are  obtained. 


14  UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 

Peach  Boot. — Where  the  soil  moisture  varies  much  in  different 
parts  of  the  orchard,  or  from  time  to  time  during  the  growing  season, 
the  peach  root  is  sometimes  the  most  satisfactory.  Soils  less  than  six 
feet  deep,  or  with  gravelly  or  hardpan  layers  at  lesser  depths,  are 
often  unsatisfactory  for  the  almond  root,  and  under  these  conditions 
the  peach  root  may  be  better.  The  peach  root  is  a  little  better  where 
irrigation  is  practiced  during  the  summer,  and  especially  where  there 
is  danger  of  an  excess  of  water  remaining  too  long  in  the  soil.  The 
peach  does  not  thrive  with  standing  water  around  its  roots,  but  will 
better  withstand  fluctuating  or  temporary  extremes  in  water  supply 
than  the  almond.    Its  union  with  the  almond  is  entirely  satisfactory. 

Davidiana  Root. — Within  the  past  seven  or  eight  years  the  United 
States  Department  of  Agriculture  has  introduced  the  seed  of  a 
Chinese  peach,  Prunus  davidiana,  the  root  of  which  is  more  resistant 
to  alkali  than  that  of  the  ordinary  peach.  This  has  been  found  to 
unite  readily  with  the  almond,  although  experiments  have  not  yet 
gone  far  enough  fully  to  determine  its  true  value.  It  gives  promise, 
however,  of  being  a  desirable  stock  for  sections  where  alkali  may  be 
troublesome. 

Unsuitable  Boots. — The  Myrobalan  plum  has  frequently  been 
recommended  as  a  stock  for  the  almond  on  poorly  drained  soils.  The 
two  make  a  strong  union,  but  the  plum  root  grows  much  more  slowly 
than  the  almond  top,  showing  that  the  trees  on  Myrobalan  root  are 
pinched-in  below  the  union.  Even  young  trees  show  the  same  effect. 
Almond  trees  on  Myrobalan  root  do  not  make  such  large  trees  nor  do 
they  bear  such  satisfactory  crops  in  any  portion  of  the  state  where  it 
has  been  possible  to  compare  them  with  the  same  varieties  on  other 
roots  in  similar  situations. 

The  apricot  is  occasionally  recommended  because  of  its  strong, 
thrifty  growth,  but  the  union  is  not  satisfactory.  The  trees  grow  well 
for  awhile,  but  before  they  reach  full  bearing,  they  generally  break  off 
at  the  union  through  the  leverage  of  the  swaying  top  in  even  moderate 
winds. 

Top-working  Old  Trees. — Where  the  varieties  in  an  old  orchard 
are  unsuitable  it  is  often  advisable  to  work  over  old  trees  to  more 
desirable  varieties.  This  may  be  done  by  grafting  or  budding.  The 
general  practice  is  to  cleft-graft  the  large  branches  at  a  convenient 
height  from  the  ground  with  two  or  more  scions,  according  to  the  size 
of  the  limb.  On  branches  where  the  scions  fail  to  grow,  it  is  advisable 
to  save  several  of  the  suckers  and  bud  into  these.  Generally  it  is 
advisable  to  leave  a  branch  asaa  sap  puller, ' '  which  may  be  removed 
the  year  after  the  grafting.     In  windy  sections  where  there  is  con- 


CIRC.  284]  THE  ALMOND  IN   CALIFORNIA  15 

siderable  danger  of  the  scions  being  blown  out,  it  is  advisable  to  graft 
about  half  of  the  tree,  one  season,  leaving  the  other  half  of  the  top 
to  serve  as  a  windbreak  until  the  top-worked  portion  has  a  chance  to 
unite  solidly.  The  other  half  of  the  tree  may  then  be  top-worked  the 
following  year. 

It  is  sometimes  desirable  to  top-work  the  orchard  with  some  other 
fruit.  Most  stone  fruits,  particularly  prunes,  plums,  and  peaches, 
unite  readily  with  the  almond.  The  apricot,  however,  cannot  be  suc- 
cessfully top-worked  on  it. 

CULTURE 

Planting. — Before  planting  almonds  the  land  should  receive  the 
same  careful  preparation  needed  by  other  fruits.  Special  care  must 
be  taken  to  insure  thorough  aeration  of  the  subsoil  by  breaking  up  all 
hardpan,  plow-pan,  or  other  compacted  layers  in  the  soil,  where 
possible. 

Distance. — Almonds  in  most  soils  should  be  planted  about  thirty 
feet  apart.  In  rich,  deep  soils  the  trees  quickly  fill  the  intervening 
space,  the  roots  occupying  the  entire  soil  area  long  before  the  tops 
touch.  In  poor,  shallow  soils,  or  soils  deficient  in  available  moisture, 
the  trees  may  not  occupy  the  entire  area  above  ground,  but  their  roots 
will  require  more  lateral  feeding  space  to  enable  the  trees  to  attain 
the  size  and  bear  the  crops  they  should. 

Trees  planted  too  close  together  often  exhaust  the  moisture  of  the 
soil  before  the  growing  season  is  over.  This  shortage  of  moisture, 
and  mites — commonly  called  red  spider — cause  loss  of  the  leaves 
long  before  the  normal  period  for  falling.  Under  such  conditions  the 
fruit-buds  are  unable  to  make  the  vigorous  growth  they  should,  and 
are  unable  to  endure  without  serious  injury  the  degree  of  frost  or 
the  other  unfavorable  conditions  that  stronger  buds  withstand. 

The  trees  must  have  plenty  of  sunlight.  If  planted  too  close 
together,  they  grow  too  high,  each  striving  for  the  light  which  is  avail- 
able only  from  above.  -  In  figure  4  the  upward  tendency  of  the  trees 
is  clearly  shown.  Such  trees,  if  properly  pruned,  have  a  much  greater 
tendency  to  send  out  numerous  water-sprouts  than  trees  which  have 
plenty  of  room  for  the  tops  to  expand  laterally.  After  the  tops  of  the 
trees  interlock  and  shut  out  the  sunlight  from  the  lower  portions, 
the  smaller  branches  and  fruit  spurs  in  these  parts  gradually  weaken 
and  die,  and  eventually  the  entire  crop  is  produced  on  or  near  the 
tops  of  the  trees,  where  alone  direct  sunlight  is  available.  The  exces- 
sive upward  growth  of  the  trees,  with  the  consequent  forcing  of  the 


16 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


fruit  bearing  to  the  top,  not  only  greatly  increases  the  difficulty  and 
cost  of  pruning,  spraying,  and  harvesting,  but  reduces  the  possible 
bearing  surface  of  the  trees. 

Setting  the  Trees. — To  secure  a  uniform  and  vigorous  stand,  the 
utmost  care  is  necessary  in  setting  out  the  trees.  The  holes  should  be 
dug  just  deep  enough  and  wide  enough  to  accommodate  the  roots 
without  crowding,  after  they  have  been  properly  trimmed.  The 
actual  size  of  hole  will  be  determined  by  the  size  of  the  average  root 


Fig.  4. — Almonds  planted  twelve  feet  apart.  Trees  in  very  weak  condition 
and  almost  entirely  defoliated  by  mites  before  harvest.  The  few  nuts  ripening 
on  the  trees  are  small  ' '  sticktights. ' '     Photograph  taken  September  21,  1915. 

system.  As  a  rule,  for  the  medium  sized,  one-year-old  tree,  a  hole 
about  fourteen  inches  wide  and  about  the  same  depth  is  sufficient. 
If  the  ground  has  been  properly  prepared,  large  holes,  except  in  cases 
of  replants,  are  of  no  advantage.  In  fact,  they  are  a  disadvantage 
for  very  often  the  tree  will  settle  and  be  too  deep.  The  most  impor- 
tant precaution  in  planting  a  tree  is  to  get  the  soil  well  firmed  around 
the  roots.  The  soil  should  be  worked  in  around  the  roots  and  firmed 
with  the  feet.  The  tree  should  be  planted  so  that  it  will  be  at  about 
the  same  depth  as  it  stood  in  the  nursery.  Do  not  plant  the  tree  too 
deep. 


/ 


ClRC.  284]  THE  AIjMOND  IN   CALIFORNIA  17 

Cultivation. — The  general  methods  of  cultivation  suitable  for  other 
orchard  fruits  may  be  used  with  almonds.  Some  people  have  thought 
that  since  the  almond  will  withstand  prolonged  periods  of  drought,  it 
will  thrive  under  careless  cultural  treatment.  This,  however,  is  not 
the  case. 

A  suitable  method  of  soil  handling  would  be  somewhat  as  follows : 
Plowing  should  be  done  in  the  spring.  If  cover  crops  are  grown, 
they  should  be  allowed  to  grow  high  in  order  to  provide  large  quan- 
tities of  humus.  Care  must  be  exercised,  however,  especially  where 
irrigation  is  not  possible,  to  prevent  the  vegetation  from  exhausting 
the  moisture  from  the  upper  soil.  The  plowing  should  be  done  early 
enough  to  be  followed  by  one  or  more  good  rains.  The  depth  of  plow- 
ing should  be  varied  from  year  to  year  in  order  to  prevent  the  forma- 
tion of  an  impervious  plow  pan.  After  plowing,  the  ground  should 
be  worked  down,  generally  with  a  disc,  before  the  plowed  surface  has 
a  chance  to  bake.  The  conditions  and  type  of  soil  will  determine 
whether  it  will  be  necessary  to  harrow  or  possibly  roll  to  firm  the  soil 
and  break  up  clods.    ^ 

Subsequent  cultivations  will  be  determined  by  weed  growth  and 
type  of  weeds.  Sufficiently  frequent  cultivations  should  be  given  to 
keep  down  weed  growth,  and  if  morning-glory  is  present,  it  will  be 
necessary  to  use  a  weed  cutter.  By  using  a  weed  cutter  once  a  week 
throughout  the  season,  the  morning-glory  may  be  practically  eradi- 
cated in  one  season.  It  is  absolutely  necessary  in  order  to  kill  the 
morning-glory  plants,  not  to  allow  them  to  show  above  ground.  It 
should  be  remembered  that  weeds  in  an  orchard,  especially  an  unirri- 
gated  orchard,  are  detrimental,  because  they  extract  much  moisture 
from  the  soil. 

Recent  investigations  indicate  that  very  little  moisture  is  lost 
through  direct  evaporation  from  the  soil  surface  under  California 
conditions.  The  greatest  loss  is  from  transpiration  through  the  leaves 
of  the  trees  and  weeds. 

When  the  land  has  been  plowed  and  brought  to  a  good  state  of 
tilth,  little  cultivation  will  be  needed  through  the  remainder  of  the 
summer,  except  to  kill  weeds,  and  put  the  soil  in  good  condition  after 
an  irrigation.  Excessive  cultivation  continued  after  the  surface  has 
been  put  in  good  condition  is  probably  a  useless  expense.6 

Cover  Crops.7 — Constant  cultivation  throughout  the  summer  pro- 
motes the  destruction  of  the  humus  and,  by  hindering  the  growth  of 


s  California  Agr.  Exp.  Sta.,  Ann.  Eept.,  1922,  p.  104. 

7  For  additional  information  on  cover  crops  see  California  Agr.  Exp.  Sta.  Cir. 
255,  1922,  and  also  California  Agr.  Exp.  Sta.  Cir.  257,  1923. 


18  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

vegetation,  prevents  the  addition  of  a  natural  supply  of  humus  to 
replace  that  which  has  been  lost. 

The  plowing  under  of  annual  winter  cover  crops  does  not  entirely 
replace  the  humus  burned  out  in  the  summer,  but  reduces  the  annual 
net  loss  and  at  the  same  time  improves  the  texture  of  the  soil. 

Melilotus  indica  (yellow  sweet-clover)  is  one  of  the  good  orchard 
cover  crops.  To  secure  satisfactory  growth,  it  must  be  planted  early 
(September),  a  factor  which  practically  prevents  its  use  where  irri- 
gation water  is  not  available. 

Very  often  vetch  (Vicia  sativa)  will  make  a  good  stand  when  late- 
planted,  though  this  is  not  always  the  case. 

In  some  sections  burr-clover  is  the  best  crop  which  can  be  used. 
It  often  reseeds  and  comes  up  year  after  year,  especially  where  fall 
irrigation  is  practiced  or  in  regions  of  early  autumn  rains.  Where 
no  irrigation  water  is  available,  the  safest  crop  is  probably  barley  or 
rye.  A  rather  new  but  promising  cover  crop  is  the  small-seeded  horse 
bean  which  generally  grows  well  in  the  cold  winter  months. 

In  addition  to  the  winter  cover  crops  named  above,  alfalfa  is  being 
successfully  used  by  some  growers  as  a  permanent  cover  or  shade 
crop  in  old  orchards  where  irrigation  is  practiced.  Too  many 
growers,  forgetting  that  the  almond  trees  are  their  main  crop,  irrigate 
and  care  for  the  alfalfa  at  the  expense  of  their  trees. 

In  some  situations  alfalfa  in  almond  orchards  increases  the 
humidity  of  the  atmosphere  sufficiently  to  aggravate  the  trouble  with 
shot-hole  and  brown  rot. 

The  following  quantities  of  seed  to  the  acre  should  give  good 
results :  Melilotus,  20-25  lbs. ;  burr-clover,  20  lbs. ;  vetch,  50  lbs. ;  small 
seeded  horse  bean,  35-45  lbs. ;  barley  or  rye,  50  lbs. 

Irrigation. — Almond  growers  are  becoming  more  convinced  that  in 
numerous  orchards  irrigation  is  advisable.  This  is  especially  true  in 
bearing  orchards  where  there  is  a  light  rainfall.  Trees  in  heavy  bear- 
ing require  more  water,  necessitating  the  addition  of  irrigation  to 
supplement  rainfall.  Where  irrigation  is  practiced  judgment  must 
be  used  in  the  amount  and  frequency  of  application  of  water.  While 
definite  directions  cannot  be  given  as  to  either,  it  is  probably  safe 
under  all  conditions  to  give  at  least  a  light  irrigation  (about  two 
acre-inches)  in  the  fall  for  seeding  the  cover  crop  and  also  for  the 
benefit  of  the  buds.  In  early  spring  if  it  is  found  that  the  winter 
rainfall  has  not  wet  the  ground  to  a  depth  of  six  feet,  the  deficiency 
should  be  made  up  by  irrigation.  Whether  it  will  pay  to  irrigate  in 
summer  has  not  been  definitely  determined,  but  keeping  up  the  vigor 


ClRC.  284]  THE  almond  IN   CALIFORNIA  19 

of  the  trees  throughout  the  season  would  no  doubt  materially  aid  in 
controlling  the  red  spider.  In  dry  years  a  large  percentage  of  the 
hulls  fail  to  open,  making  hulling  impossible.  When  the  hulls  begin 
to  split  it  is  advisable  to  irrigate.  This  reduces  the  number  of  "  stick- 
tights.  " 

The  above  discussion  applies  to  middle-aged  and  old  trees.  Young 
trees,  eight  to  ten  years  old,  may  do  very  well  without  any  irrigation 
whatever  if  the  average  rainfall  is  sixteen  inches  or  more. 

Numerous  methods  of  applying  water  may  be  used.  The  check 
and  furrow  systems  are  most  generally  employed.8 

Fertilization. — Little  or  no  systematic  work  has  been  done  up  to 
the  present  time  in  the  use  of  commercial  fertilizers  on  almonds.  The 
use  of  barnyard  manure  is  desirable  wherever  obtainable.  The  value 
of  almond  hulls  as  fertilizer  is  doubtful,  because  of  the  difficulty  of 
bringing  about  their  thorough  decay.  Because  of  the  high  percentage 
of  tannin  they  contain,  it  is  inadvisable  to  use  more  of  them  than 
would  naturally  fall  from  the  tree.  The  use  of  lime  to  correct  soil 
acidity  and  to  improve  the  texture  of  heavy  soils  is  desirable  if  the 
cost  is  not  prohibitive. 

PRUNING^ 

Pruning  properly  begins  with  the  training  of  the  young  tree 
the  first  summer  in  the  orchard.  At  the  time  of  planting  the  tree 
is  generally  cut  back  to  a  whip  about  twenty-seven  inches  long.  In 
rare  cases,  when  good  nursery  laterals  occur  where  wanted,  they 
may  be  saved  and  shortened  to  eight  or  ten  inches.  As  a  rule,  how- 
ever, all  the  nursery  laterals  are  cut  off.  The  framework  branches 
must  be  grown  from  dormant  buds  or  from  adventitious  buds  which 
arise  around  the  wounds  caused  by  removing  the  nursery  laterals.  In 
the  spring  (April  or  May)  much  good  work  in  training  the  framework 
may  be  done  by  going  over  the  trees  carefully  and  selecting  the 
branches  desired  for  the  framework.  At  this  time  the  growth  is  only 
a  few  inches  long,  and  the  undesirable  twigs  are  easily  subdued  by 
pinching  out  their  terminals.  This  will  encourage  the  growth  of  those 
selected  for  framework  branches.  These  should  be  allowed  to  grow 
untouched.  The  undesirable  branches  should  not  be  removed  entirely 
because  their  leaves  manufacture  plant  food  and  by  shading  help  to 
prevent  sunburn  of  the  trunk. 


s  For  methods  of  applying  water  see  U.  S.  Dept.  of  Agr.  Farmers'  Bull.  8S2, 
1917. 

o  For  additional  data  on  priming  see  California  Agr.  Exp.  Sta.  Bull.  313,  1922, 
and  also  California  Agr.  Exp.  Sta.  Bull.  386,  1925. 


20 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


If  a  tree  is  allowed  to  grow  the  first  summer  without  this  treat- 
ment, three  to  five  of  the  uppermost  buds  will  develop  into  good  strong 
branches  by  the  end  of  the  growing  season,  while  only  short  twigs 
will  develop  from  the  buds  lower  down  on  the  trunk.  The  latter  can- 
not be  used  as  framework  branches.  In  this  case,  it  will  be  necessary 
to  select  the  three  framework  branches  all  arising  from  practically 
the  same  point  on  the  tree,  a  condition  which  in  later  years  causes 
crowding  and  the  formation  of  water  pockets  (fig.  5). 


Fig.  5. — The  result  of  selecting  branches  arising  from  one  point  on  a  main 
trunk.  In  this  so-called  water  pocket  note  the  entire  blade  of  the  knife  is  under 
water.  This  photograph  is  of  a  ten-year-old  almond  tree.  The  trouble  is  only 
just  beginning,  and  unless  immediate  steps  are  taken  for  its  remedy  the  usefulness 
of  the  tree  will  be  shortened  many  years.     From  Bull.  313,  California  Exp.  Sta. 


The  best  type  of  head  is  one  in  which  the  branches  are  spaced  as 
far  apart  as  possible  along  the  trunk.  The  ideal  is  to  have  three 
branches  (with  more  it  is  impossible  to  avoid  crowding),  spaced  about 
six  inches  apart  and  arranged  spirally  around  the  trunk,  forming 
equal  angles  of  about  120  degrees.  The  only  way  to  get  strong 
branches  where  they  are  desired  is  to  pinch  the  tips  of  all  badly 


CIRC.  284]  THE  ALMOND  IN  CALIFORNIA  21 

placed  shoots.  This  diverts  the  growth  into  those  suitably  placed.  It 
is  advisable  to  go  over  the  orchard  again  in  June  to  subdue  additional 
undesirable  growth. 

Pruning  One-year-old  Trees. — The  first  winter's  pruning  may  be 
done  at  any  time  after  the  leaves  fall,  approximately  one  year  after 
planting.  If  summer  pinching  has  been  done,  there  will  be  very  little 
to  do  except  to  cut  back  the  three  scaffold  branches  to  from  fifteen  to 
thirty  inches  to  a  lateral  if  possible — according  to  the  variety  of 
almond,  and  the  growth  the  tree  has  made. 

On  account  of  its  spreading  habit  of  growth  a  Drake  will  have  to 
be  headed  more  severely  than  an  upright  variety  such  as  the  Ne  Plus 
Ultra  or  I.  X.  L.  In  cases  where  trees  have  made  a  very  vigorous 
growth  during  the  first  summer  in  the  orchard,  it  may  be  desirable 
to  head  them  when  they  have  made  a  growth  of  fifteen  to  thirty 
inches.  A  secondary  branching  may  thus  be  secured  during  the  first 
summer.  In  this  case  the  first  winter's  pruning  will  consist  of  a 
thinning  only,  since  a  sufficient  number  of  framework  branches  have 
been  secured  (five-seven  at  about  five  feet  from  the  ground).  If  the 
trees  have,  for  some  reason,  made  very  poor  growth  during  the  first 
season,  they  should  receive  no  pinching  out  in  the  summer  and  little 
or  no  pruning  in  the  first  winter  so  that  they  may  have  as  much  leaf 
surface  as  possible  to  build  up  the  tree  and  make  a  strong  healthy 
growth  the  second  season. 

Figure  6  shows  a  Nonpareil  almond,  before  pruning,  after  one 
season's  growth  in  the  orchard.  At  the  time  of  planting  the  nursery 
laterals  were  saved  and  headed  at  "A."  Figure  7  shows  the  same 
tree  as  figure  6  after  pruning. 

Pruning  During  the  Second  Season. — When  growth  starts  the 
second  spring,  numerous  sprouts  will  be  produced  around  pruning 
wounds  and  also  from  dormant  buds  where  they  are  not  wanted.  It 
is  a  good  plan  to  go  through  the  orchard  in  early  May  or  whenever 
these  sprouts  are  eight  to  ten  inches  long  and  pull  off  or  cut  out  those 
not  wanted  and  pinch  back  those  which  will  make  desirable  fruit 
spurs  (the  less  vigorous  ones).  The  removal  at  this  time  of  undesir- 
able branches  which  are  likely  to  grow  at  the  expense  of  the  desirable 
■framework  branches  is  also  recommended.  Since  the  almond  makes 
numerous  lateral  branches  it  is  not  usually  necessary  or  even  desir- 
able to  give  any  heading  to  the  framework  branches  the  second  season. 

If  no  spring  pinching  has  been  given  during  the  second  spring 
and  summer,  it  will  be  necessary  to  remove  the  watersprouts  and  ill- 
placed  branches.     Occasionally,  when  a  tree  has  made  an  unsym- 


22 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


Fig.  6. — One-year-old  Nonpareil  before  pruning.     At  the  time  of  planting  the 
nursery  laterals  were  saved  and  headed  at  "A. " 


Circ.  284] 


THE  ALMOND  IN   CALIFORNIA 


23 


metrical  growth,  a  watersprout  may  be  used  to  advantage  for  a  frame- 
work branch  if  growing  in  the  proper  position  to  fill  a  vacancy.  Gen- 
erally no  heading  is  necessary,  especially  if  the  tree  has  five  to  seven 
branches  and  sufficient  spread. 


Fig.    7. — Same   tree   as   fig. 
laterals  headed  moderately. 


6   after   pruning.      Thinned   to   laterals   and   the 


Pruning  the  Third  and  Fourth  Years. — If  the  trees  have  been 
pruned  as  above  outlined  (it  is  assumed  that  soil,  moisture,  etc.,  are 
favorable  for  good  vigorous  growth),  the  only  pruning  necessary  will 


24 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


be  a  thinning  out  with  no  heading  (fig.  8).  These  trees  should 
produce  a  considerable  crop  of  nuts  the  fourth  summer  and  should 
thereafter  be  handled  as  bearing  trees. 


Pig.  8. — Nonpareil  almond.     Three  years  old.     After  pruning.     Thinned  only. 

Pruning  Bearing  Trees. — If  young  almond  trees  have  been  prop- 
erly trained  and  pruned,  the  bearing  trees  should  not  be  hard  to 
prune.  The  commercial  practice  in  almond  pruning  consists  mainly 
in  the  removal  of  watersprouts  and  branches  averaging  one-half  inch 


Cmc.  284] 


THE  ALMOND  IN   CALIFORNIA 


25 


in  diameter,  no  attention  being  given  to  the  one-year-shoots  (fig.  9). 
Occasionally  it  will  be  necessary  to  remove  a  larger  branch  as  it  begins 
to  interfere  or  cause  crowding.  It  is  necessary  to  keep  the  trees  open 
so  that  the  sun  can  filter  down  through  the  leaves  and  maintain  a 
healthy  condition  in  the  lower  buds  and  fruit  spurs — otherwise  the 
fruiting  area  will  be  confined  to  the  outer  area  of  the  tree.  This 
practice  also  facilitates  harvesting.  Normally,  bearing  almond  trees 
are  not  expected  to  make  more  than  from  eight  to  fifteen  inches  of 


w    1 


\    :■/(/'/ 


,A  * 


Fig.  9. — Six-year-old  Nonpareil.     ' '  Moderately  pruned. ' ' 


new  wood  growth  each  year.  If  trees  are  making  much  more  growth, 
it  may  be  advisable  to  cease  pruning  for  several  years.  This  is  likely 
to  throw  the  trees  into  heavy  production  and  thus  slow  down  vegeta- 
tive growth.  After  regular  bearing  is  established,  a  moderate  pruning 
should  be  given  to  get  the  trees  back  into  proper  shape.  On  the  other 
hand,  if  they  are  making  little  or  no  growth,  some  of  the  fruiting 
branches  should  be  removed.  This  will  invigorate  the  trees  (fig.  10). 
Very  often,  however,  the  lack  of  growth  is  due  to  soil  moisture  con- 
ditions and  cannot  be  materially  influenced  by  pruning  alone. 


26 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


KEJUVENATION  OF  OLD  TKEES 

Through  one  cause  or  another,  old  trees  sometimes  reach  a  con- 
dition where  production  is  so  low  that  they  are  no  longer  profitable. 
The  question  which  confronts  the  grower  is  what  to  do  with  the  trees 
to  get  them  back  to  profitable  production.  If  the  trees  are  sound, 
that  is,  not  affected  with  severe  infections  of  crown  gall  or  heart  rot, 
and  not  growing  under  adverse  conditions  such  as  shallow  soil,  under- 
lying hardpan,  or  lack  of  moisture,  they  can  very  often  be  rejuvenated 
by  cultural  treatment. 


Fig.    10. — Twenty-seven-year   old   Ne   Plus  Ultra   after   having  been    severely 
thinned.     This  tree  had  not  been  pruned  for  six  or  eight  years. 


Sometimes  a  thorough  spraying  to  destroy  the  pests  and  the  addi- 
tion of  irrigation  is  sufficient.  Very  often  a  more  or  less  severe  prun- 
ing will  be  necessary.  Generally  this  pruning  should  consist  of  the 
removal  of  a  considerable  number  of  rather  large  branches.  In  order 
to  prevent  sunburn,  the  thinning  out  and  opening  up  of  the  trees 
should  be  gradual.  Frequently  the  removal  of  a  larger  number  of 
smaller  branches  all  over  the  tree  is  more  advisable  than  removing  a 
large  limb  here  and  there. 

Under  certain  conditions  it  may  be  best  to  dehorn  the  trees  about 
six  feet  from  the  ground  and  form  a  new  head  from  the  suckers  which 
arise  near  the  end  of  the  stubs.     This  method  is  not  always  satis- 


ClRC.  284]  THE  ALMOND  IN   CALIFORNIA  27 

factory,  especially  in  windy  sections.  The  new  shoots  do  not  have  a 
very  strong  union  with  the  stubs  and  after  they  come  into  bearing 
will,  from  time  to  time,  blow  off. 

ORCHARD  HEATING  FOR  FROST  PREVENTION^ 

On  account  of  their  early  blossoming  habit  the  almonds  are  fre- 
quently injured  by  frost.  Recently  considerable  interest  has  been 
shown  in  methods  of  protecting  them  from  this  danger.  The  use  of 
orchard  heaters  in  some  districts  has  become  a  common  and  successful 
practice.  It  is  possible  economically  to  control  several  degrees  of 
frost  for  three  or  four  or  possibly  more  nights  by  a  judicious  use  of 
heaters. 

The  best  type  of  heater10  for  almond  orchards  has  not  been 
thoroughly  worked  out  as  yet.  Both  the  "lardpail"  or  open  type  and 
the  improved  stack  type  of  heater  are  being  used. 

At  least  seventy-five  one  or  two-gallon  lardpail  heaters  to  the  acre 
are  necessary  to  control  temperatures  as  low  as  27  or  28  degrees  F. 
Probably  not  over  100  pots  to  an  acre  would  be  needed  at  most.  A 
smaller  number  of  the  stack  heaters  are  sufficient.  Double  the  number 
of  pots  should  be  placed  around  the  outside  especially  on  the  wind- 
ward side. 

The  gravity  of  oil  best  suited  for  orchard  heating  is  between  20 
and  25  degrees  Baume.  It  is  essential  that  it  be  as  free  as  possible 
from  impurities  such  as  sulfur.  During  the  spring  of  1917,  orchard 
heating  was  done  very  extensively  in  some  districts  of  the  state  while 
the  trees  were  approaching  full  bloom.  As  the  season  progressed,  it 
became  apparent  that  some  serious  injury  had  been  done  by  the  heat- 
ing, for  the  bulk  of  the  blossoms  fell  off  and  the  leaves  turned  yellow  in 
streaks  as  if  burned  by  an  acid.  It  seemed  as  though  the  pistils  of  the 
flowers  and  the  young  leaves  had  absorbed  sulfur  dioxide  gas  (a 
product  of  oil  combustion,  where  sulfur  is  contained  in  the  oil),  which 
in  uniting  with  the  dews  had  formed  sulfurous  acid,  which  had  done 
the  damage.  Had  the  heating  been  done  only  after  the  trees  had 
passed  full  bloom,  a  much  heavier  set  of  nuts  might  have  been  secured, 
since  the  small  fruits,  where  they  had  formed,  seemed  to  have  been 
uninjured,  only  the  pistils  of  the  flowers  having  been  affected,  prob- 
ably preventing  pollination  and  fertilization  of  the  ovules. 

The  time  of  heating  is  therefore  a  very  important  point.  Almond 
blossoms  become  progressively  more  tender  to  frost  as  they  advance 


io  Additional  information  may  be   obtained   from  the  Almond  Growers'   Ex- 
change Bulletin  entitled,  " Frost  Protection— Orchard  Heating,"  pp.  1-8,  1923. 


28  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

in  development.  With  their  petals  on,  they  are  not  nearly  so  tender 
as  they  are  after  the  petals  have  fallen.  They  reach  their  most  tender 
stage  after  the  calyx  shucks  have  fallen  and  before  the  fruits  are  the 
size  of  a  pea.  Ordinarily,  orchard  heating  before  the  trees  have 
passed  full  bloom  is  a  waste  of  time  and  material  and  is  often 
injurious.  The  most  necessary  time  for  heating  is  usually  during  the 
two  or  three  weeks  after  the  bulk  of  the  petals  have  fallen,  unless 
temperatures  below  28  to  29  degrees  are  encountered  before  that  time. 
The  most  complete  treatise  on  orchard  heating  is  U.  S.  D.  A.  Farmers' 
Bulletin  No.  1096,  entitled  "  Frost  and  the  Prevention  of  Damage 
by  It." 

CEOP  HANDLING 

Harvesting. — The  harvesting  of  the  crop  should  begin  as  soon  as 
the  hulls  have  opened  to  their  fullest  extent,  and  no  time  should  be 
lost  in  completing  the  work.  The  nuts  in  the  center  of  the  tree  are 
the  last  to  ripen  and  so  may  be  used  as  indicators.  If  harvesting  is 
begun  too  early,  the  nuts  will  cling  to  the  tree  rather  tenaciously  and 
require  very  vigorous  knocking  to  loosen  them.  On  the  other  hand, 
if  they  are  allowed  to  hang  too  long  after  ripening,  a  number  of 
difficulties  may  be  encountered.  They  may  be  blown  to  the  ground 
by  light  winds  and  the  cost  of  gathering  be  increased,  as  quite  com- 
monly occurs  with  the  Peerless ;  or  the  hulls  may  dry  up  and  in  doing 
so  close  around  the  nuts  to  a  greater  or  less  extent  and  add  to  the  cost 
and  difficulty  of  hulling.  This  is  most  noticeable  with  the  Nonpareil. 
Strong  winds  will  break  off  a  great  many  of  the  nuts  of  any  of  the 
varieties,  and  promptness  is  doubly  essential  where  there  is  any  like- 
lihood of  such  winds  occurring  during  the  harvest  season.  Depreda- 
tions by  birds  may  cause  serious  losses,  especially  with  the  soft  and 
paper-shell  varieties.  Infestation  by  worms  may  often  be  quite 
serious  in  the  papershell  varieties,  when  they  are  allowed  to  hang  too 
long.  In  case  of  damp  or  foggy  weather,  the  shells  turn  dark  and 
sometimes  commence  to  mildew,  requiring  heavier  bleaching  to 
brighten  them  sufficiently  for  market  demands.  Rain  stains  can  never 
be  removed  entirely  by  ordinary  bleaching. 

The  crop  is  harvested  by  knocking  the  ripened  nuts  and  hulls  with 
long  poles  onto  sheets  spread  on  the  ground  under  the  trees.  The 
knocking  should  be  done  near  the  portions  of  the  trees  where  the  nuts 
are  borne  and  by  striking  a  number  of  light,  quick  blows,  rather  than 
by  a  heavy  blow  aimed  to  jar  a  large  branch.  This  method  avoids 
injury  to  the  bark  by  bruising  and  will  accomplish  the  work  in  less 


Circ.  284] 


THE  ALMOND  IN   CALIFORNIA 


29 


time.  The  blows  should  always  be  delivered  squarely  against  the 
branch.  A  glancing  blow  will  tear  the  bark  and  break  off  a  great 
many  fruit  spurs,  thus  reducing  the  bearing  surface  for  the  next  year. 
For  this  reason  harvesters  must  be  watched  closely  all  the  time  to 
insure  the  proper  use  of  the  poles.  The  sheets,  two  in  number,  are 
spread  under  the  trees  so  they  will  overlap  and  catch  all  the  nuts  that 
fall  (see  fig.  11).  When  sufficiently  loaded  with  nuts  to  make 
dragging  the  sheets  from  one  tree  to  another  difficult,  they  are 
emptied  into  lug  boxes  or  bags  and  sent  to  the  huller. 


Fig.  11. — Harvesting  almonds  by  knocking  onto  sheets  spread  on  ground. 


The  character  of  the  harvesting  equipment  may  vary  consider- 
ably, according  to  the  acreage,  character  of  trees  and  ground,  time 
required,  capital  available,  and  the  ideas  of  the  owner.  Some  growers 
use  heavy  poles  of  pine,  spruce,  or  fir,  while  others  prefer  the  lighter 
bamboo  poles.  The  heavy  poles  are  from  1%  to  2  inches  in  diameter 
at  the  base  and  from  %  to  1  inch  in  diameter  at  the  top.  Experience 
has  shown  that  poles  of  this  type  over  20  feet  in  length  are  unwieldy, 
and  not  only  swing  slowly  but  do  more  damage  because  of  the  greater 
difficulty  of  control.    Most  growers  prefer  16-foot  poles  with  a  few  20- 


30 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


foot  ones  for  use  in  the  tops  of  the  taller  trees.  Where  the  tops  cannot 
be  reached  with  these,  the  men  climb  into  the  trees  with  shorter  poles. 
The  bamboo  poles  used  are  about  24  feet  long,  and  because  of  their 
lightness,  can  be  used  with  greater  speed.  Bamboo  poles  with  short 
internodes  should  be  selected,  as  they  are  less  likely  to  break.  Break- 
age may  also  be  reduced  by  storing  the  poles  in  a  cool  place  where 
drying-out  will  not  be  excessive. 

The  sheets,  which  are  made  of  7  to  12-ounce  duck,  range  in  size 
from  12  by  24  to  24  by  48  feet.  They  need  not  be  much  longer  than 
the  longest  diameter  of  the  tree.  To  prevent  mildew  and  rotting  of 
the  fabric,  the  sheets  should  be  boiled  in  a  solution  of  tannin  before 
being  used.     Sheets  thus  treated  last  much  longer. 

Some  growers  have  contrivances  by  which  sheets  are  mounted  on 
sleds  or  wheels.  The  principal  objection  to  such  an  arrangement 
is  that  the  sled  or  wheeled  frame  must  be  made  in  two  sections,  one 
for  each  side  of  the  tree,  which  increases  the  cost  of  the  operation 
because  the  horses  can  be  used  for  nothing  else  while  the  harvesting 
is  in  progress.  On  the  other  hand,  when  moved  by  dragging  on  the 
ground,  sheets  will  wear  out  in  two  or  three  seasons,  while  with  the 
sled  or  wagon  method  they  will  last  from  six  to  ten  years  longer.  The 
two  wagons  shown  in  figure  12,  each  12  by  24  feet,  cost  between  $60 
and  $70  about  the  year  1914.    The  canvas  portion  is  of  8-ounce  duck. 


Fig.  12. — Portable  almond  sheets  mounted  on  wheels  as  used  by  N.  J.  Lund, 
Oakdale,  California,  1916. 


CIRC.  284]  THE  ALMOND  IN   CALIFORNIA  31 

By  this  method  the  knockers  can  gather  ten  lug  boxes  before  empty- 
ing. The  work  can  be  done  much  faster  with  wagons.  When  sleds 
are  used,  one  sheet  is  fastened  lengthwise  on  the  right  side  of  the 
left-hand  sled  and  another  on  the  left  side  of  the  right-hand  sled. 
More  recently,  single  sleds  have  been  devised  with  the  two  sheets 
extending  lengthwise  on  either  side  of  the  tree.  The  Division  of 
Agricultural  Engineering  of  the  University  of  California  have  avail- 
able plans  and  specifications  for  such  a  sled. 

Hulling. — After  harvesting,  the  almonds,  hulls  and  all,  are  taken 
to  the  huller  while  still  moist.  If  they  become  dry  before  hulling  they 
must  be  dipped  in  water  or  the  shells  will  be  broken.  All  hulling  was 
formerly  done  by  hand,  and  this  is  still  done  where  only  small  lots 
are  to  be  handled.  The  invention  of  machinery  for  this  purpose  has 
reduced  the  cost  of  hulling  from  60  to  80  per  cent,  for  most  outfits 
separate  the  hulls  from  the  nuts  before  they  leave  the  machine.  Some 
of  the  hand  hullers  consist  simply  of  the  hulling  portion  of  the  large 
power  machine  without  the  separating  screens.  These  cost  about 
one-sixth  or  one-seventh  as  much  as  the  large  machines,  and  where 
a  man  has  a  small  acreage  and  is  too  far  away  to  haul  to  a  large 
huller,  a  hand  machine  will  greatly  facilitate  the  work,  even  though 
the  final  separation  must  be  done  by  hand. 

There  are  many  different  kinds  of  hulling  and  separating  machines 
now  in  operation  in  California,  all  invented  by  California  almond 
growers.  The  first  one  made  was  the  Read  " Sure-Pop''  almond 
huller.  This  is  now  manufactured  in  three  sizes  by  the  Schmeiser 
Manufacturing  Company,  Davis,  California.  The  No.  3  huller,  which 
is  generally  best  for  orchards  of  less  than  ten  acres,  may  or  may  not 
be  equipped  with  a  separating  device.  If  it  has  no  separator,  it  may 
be  operated  by  hand;  otherwise  a  small  engine  or  motor  is  needed. 
The  No.  2  hullers  both  hull  and  separate  and  are  operated  only  by 
power.  They  should  pay  in  orchards  of  ten  acres  or  more.  The 
No.  1  is  the  largest  made  and  is  for  use  in  orchards  of  100  acres  or 
more. 

The  Beach  huller  is  of  more  recent  origin,  having  been  in  use  only 
since  1895.  It  was  invented  by  J.  E.  Beach  of  Fairoaks,  California, 
and  is  being  manufactured  by  him.  Both  sizes  of  this  machine  are 
power  outfits ;  they  are  doing  satisfactory  work  at  the  present  time. 

A  third  huller  is  that  made  by  C.  U.  Reams  of  Suisun.  More 
recently,  hullers  have  been  invented  and  are  being  manufactured  as 
follows : 


32  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

The  Miller  Huller,  manufactured  by  L.  L.  Miller,  Ripon,  Cali- 
fornia. 

The  Stephens  Huller,  manufactured  by  the  Bean  Spray  Pump 
Company,  San  Jose,  California. 

The  Martinette  Huller,  manufactured  by  F.  L.  Martinette,  Chico, 
California. 

The  Vaughan  Huller,  manufactured  by  L.  K.  Vaughan,  Wood- 
land, California. 

An  unnamed  huller,  manufactured  by  Smith  Manufacturing  Com- 
pany, San  Jose,  California. 

The  efficiency  of  these  hullers  depends  largely  upon  the  speed  of 
the  machine  and  upon  the  condition  of  the  almonds  in  the  hulls.  If 
the  machine  runs  too  fast,  the  almonds  are  broken  and  injured,  and 
if  it  runs  too  slowly,  many  of  the  almonds  are  not  hulled.  If  the 
almonds  are  allowed  to  hang  on  the  trees  too  long,  the  hulls  become 
dry  and  leathery,  and  the  difficulty  of  hulling  is  greatly  increased. 
Dipping  in  water  in  such  cases  may  help  to  overcome  this  difficulty 
to  a  limited  extent. 

The  papershell  varieties,  notably  the  Nonpareil,  are  much  more 
difficult  to  hull  without  breaking  the  shells  than  are  the  harder  shelled 
varieties.  The  Nonpareil  hull  has  a  tendency  to  close  around  the  nut 
on  drying,  making  hulling  very  difficult. 

Often  when  the  moisture  supply  in  the  soil  is  exhausted  before  the 
nuts  are  ripe,  or  when  the  loss  of  leaf  surface  due  to  mites  is  serious 
before  ripening,  the  hulls  open  only  slightly  or  not  at  all,  but  dry 
onto  the  shell  of  the  nut.  Such  "stick-tights"  can  be  disposed  of 
profitably  only  by  allowing  them  to  dry  thoroughly,  after  which  they 
are  cracked  and  sold  as  ' '  meats. ' ' 

After  the  hulling  operation,  all  almonds  must  be  gone  over  by 
hand  to  remove  pieces  of  hulls  and  inferior  or  gummy  nuts.  Where 
canvas  drapers  are  not  available  for  sorting  directly  from  the  huller, 
the  nuts  are  piled  in  hoppers  and  sorted  on  benches  beneath  them. 

Drying. — Immediately  after  the  sorting,  the  nuts  are  spread  on 
trays  and  thoroughly  dried  in  the  sun.  In  the  interior  valleys  during 
hot,  dry  weather  the  nuts  will  sometimes  dry  so  quickly  that  by  the 
time  the  sorting  from  hoppers  is  completed,  the  nuts  are  sufficiently 
dry.  The  grower  must  be  certain,  however,  that  such  is  the  case 
before  the  almonds  are  delivered  to  the  warehouse.  The  nuts  are 
sufficiently  dry  when  the  kernels  will  break  without  bending.  Quick 
drying  seems  essential  to  prevent  the  excessive  darkening  of  the  shell. 


CIRC.  284]  THE  ALMOND  IN   CALIFORNIA  33 

Bleaching. — The  trade  demands  an  almond  with  a  bright  golden- 
yellow  shell.  In  the  earlier  history  of  the  almond  industry,  the 
growers  bleached  their  own  almonds.  As  a  consequence,  there  was  no 
uniformity  in  the  product.  At  the  present  time  the  associations 
advise  that  the  almonds  be  delivered  unbleached,  as  they  have  per- 
fected machinery  for  bleaching  and  are  thus  able  to  produce  a  uni- 
formly bleached  product. 

Their  method  in  general  consists  of  subjecting  the  almonds  to  a 
low  steam  pressure  for  10  to  20  minutes  in  order  to  moisten  the  shell. 
They  are  then  exposed  to  sulfur  fumes  for  10  to  30  minutes.  One  to 
three  pounds  of  the  best  grade  of  flowers  of  sulfur  is  necessary  to 
bleach  one  ton  of  almonds.  Proper  bleaching  does  not  affect  the 
almond  in  any  way.  However,  over-bleaching  produces  a  sickly 
yellow  or  whitish  colored  shell  and  also  causes  the  kernel  to  deterior- 
ate and  become  rancid. 

Sacking. — During  the  preliminary  handling  of  almonds,  ordinary 
grain  sacks  are  commonly  used.  After  bleaching,  in  which  condition 
they  are  ready  for  market,  they  are  put  in  standard  almond  bags, 
measuring  20  by  40  inches  and  weighing  1%  pounds.  The  weight 
of  a  bag  of  almonds  varies  not  only  with  the  variety  but  also  with 
the  year  and  locality  in  which  it  is  produced.  For  selling  purposes 
the  California  Almond  Growers'  Exchange  estimates  weights  of  differ- 
ent varieties  to  be  as  follows :  Nonpareil,  85  pounds  to  the  bag ;  I.  X. 
L.,  80  pounds;  Ne  Plus  Ultra,  75  pounds;  Drake,  90  to  100  pounds; 
Languedoc,  100  pounds;  and  hardshell  almonds,  100  to  120  pounds. 
The  bags  will  be  changed  with  the  1924  crop,  and  will  measure 
28  by  40  inches,  and  weigh,  when  filled,  about  as  follows :  Nonpareil, 
I.  X.  L.,  and  Ne  Plus  Ultra,  85-90  pounds;  Drake,  100  pounds;  Texas, 
105-110  pounds;  hardshells,  120-130  pounds. 

Shelling. — The  increasing  popularity  of  shelled  almonds,  and  the 
limited  market  for  unshelled  ones  during  the  past  few  years,  have 
made  it  imperative  to  give  attention  to  methods  of  shelling.  The 
California  Almond  Growers'  Exchange  has  perfected  machinery 
which  together  with  increased  tariff  duties  has  enabled  it  to  market 
large  quantities  of  shelled  almonds  during  the  1923-24  season.  Thus 
there  was  but  little  carry-over  into  the  1924  crop  season  and  none 
into  the  1925.  A  small  proportion  of  the  shelled  almonds  marketed — 
usually  not  more  than  thirty  pounds  to  the  ton — are  accidentally 
shelled  during  the  hulling  process. 

Recently  a  large  proportion  of  the  Texas  variety  has  been  shelled 
and  sold  successfully. 


34  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Papershells,  however,  are  the  varieties  most  commonly  marketed 
in  this  way,  for  two  reasons :  (1)  their  kernels  do  not  break  so  readily 
in  the  shelling  process,  and  (2)  the  percentage  of  kernel  is  much 
higher  than  in  the  harder  shelled  varieties. 

Grading. — Though  grading  almonds  for  size  is  not  practiced  at 
present,  it  probably  will  be  within  the  next  few  years.  Grading  for 
quality,  however,  is  done  regularly  by  testing  an  entire  lot  rather 
than  by  attempting  to  separate  inferior  nuts.  All  lots  free  from 
worms  or  gummy  nuts  and  having  a  required  percentage  of  good 
kernels — 90  to  95  per  cent,  according  to  the  conditions  of  the  market 
and  of  the  crop  as  a  whole — are  considered  standard  grades,  and  are 
sold  on  guarantee.  All  lots  which  cannot  pass  this  test  are  sold  on 
sample,  and  therefore,  on  their  own  individual  merits. 


MARKETING 

Exchange  Organization. — The  marketing  of  the  almond  crop  of 
California  is  at  present  on  a  firmer  basis  than  at  any  time  in  the  past. 
Before  1910  there  was  little  or  no  cooperation  among  growers,  and 
the  buyers  had  everything  their  own  way.  In  May  of  that  year,  how- 
ever, Mr.  J.  P.  Dargitz,  an  almond  grower  near  Acampo,  California, 
successfully  organized  the  California  Almond  Growers'  Exchange, 
consisting  of  nine  local  sub-associations,  with  a  total  membership  of 
230  growers.  The  Exchange  started  business  with  $1000,  borrowed 
capital,  personally  guaranteed  by  the  directors.  On  June  1,  1918, 
there  were  twenty-two  sub-associations  representing  about  2000  grow- 
ers, and  controlling  about  three-fourths  of  the  crop.  On  April  1, 
1924,  the  association  had  a  membership  of  3359,  controlling  70  per 
cent  of  the  crop.  All  members  are  on  a  five-year  contract  basis.  The 
Exchange  now  is  not  only  out  of  debt  but  has  assets  of  about  $400,000, 
including  warehouses,  a  central  shelling  plant,  and  other  property. 
At  the  same  time,  the  growers  have  been  receiving  about  50  per  cent 
more  for  their  almonds  then  before  the  Exchange  was  organized. 

The  success  of  the  Exchange,  with  the  consequent  higher  prices 
to  the  grower,  has  resulted  in  a  large  increase  in  the  acreage  of 
almonds  in  California.  This  increase  is  making  it  necessary  to 
develop  new  markets  to  absorb  the  consequent  greater  tonnage,  which 
can  be  done  satisfactorily  only  by  cooperative  effort. 

Until  1923,  California  almonds  were  marketed  chiefly  in  the  shell, 
though  a  small  quantity  had  been  cracked  annually  to  supply  west- 


ClRC.  284]  THE  ALMOND  IN   CALIFORNIA  35 

ern  brokers  and  confectioners.  Virtually  all  of  these  were  sold  west 
of  the  Rocky  Mountains.  During  the  1923  crop  season,  however,  the 
Exchange  sold  over  1,300,000  pounds  of  shelled  almonds. 

European  Competition. — European  growers  who  send  their  crops 
to  the  United  States  largely  as  "meats"  had  practically  a  monopoly 
of  the  shelled  almond  business  until  1923.  The  unshelled  Tarragonas, 
Princess,  etc.,  shipped  to  America  come  into  direct  competition  with 
the  I.  X.  L.,  Drake,  Languedoc,  and  other  California  almonds,  all  of 
which  are  unshelled.  The  amount  of  unshelled  almonds  imported  is 
about  equal  to  the  California  production.  The  Jordan,  Valencias, 
and  other  varieties  constituting  the  bulk  of  the  importations,  how- 
ever, come  shelled.  The  Jordan,  because  of  its  superior  quality,  is 
almost  in  a  class  by  itself  and  does  not  at  present  cause  serious  com- 
petition with  the  California  product.  The  Princess  and  other  almonds 
of  the  same  type  are  very  similar  to  the  California  shelling  varieties 
and  are  serious  competitors  when  offered  in  the  same  markets.11 

Storing. — Almonds  become  rancid  if  stored  in  warm  or  damp 
places.  If  they  have  been  properly  cared  for  during  the  handling 
process  to  prevent  worm  infection,  and  have  been  thoroughly  cured, 
however,  they  will  keep  satisfactorily  in  suitable  storage  for  a  year  or 
more  while  awaiting  removal  or  sale.  The  places  where  they  are 
stored  should  be  uniformly  cool,  dry  and  with  ample  ventilation. 

COST  OF  PBODUCTION 

The  amount  and  kind  of  equipment  of  the  average  almond  orchard 
is  extremely  variable.  The  larger  and  more  progressive  orchards  are 
usually  wTell  equipped  with  all  the  necessary  tools  and  power.  Many 
small  growers,  however,  can  not  afford  all  the  machinery  necessary 
for  running  their  places.  Most  orchardists  have  their  own  tillage 
and  harvesting  equipment,  though  some  prefer  to  depend  upon  their 
neighbors  to  do  their  hulling  by  contract. 

In  addition  to  the  ordinary  orchard  equipment,  the  almond  grower 
needs  special  equipment  for  harvesting,  hulling,  and  drying.  This 
includes  canvas  sheets,  poles  for  knocking,  lug  boxes  or  sacks,  a  huller, 
sorting  tables  or  bins,  trays,  and  sacks  for  delivery  to  the  warehouse. 
Sheets  cost  from  $20  to  $100  according  to  the  size  and  quality ;  poles 
15  cents  or  more;  lug  boxes  35  cents;  hullers  $150  to  $1200;  trays 


ii  The  increasing  popularity  of  shelled  almonds  makes  it  advisable  that  the 
American  markets  be  made  familiar  with  the  California  shelled  product,  and  that 
its  sale  be  extended  as  quickly  as  possible.  This  is  indeed  necessary  because  it  has 
been  found  impossible  to  dispose  of  the  whole  of  the  present  annual  production 
in  the  shell,  and  the  prospects  are  for  a  greater  production  in  the  near  future. 


36  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

about  75  cents;  sacks  about  15  cents;  sorting  tables  or  bins  are  gen- 
erally made  by  the  grower  at  the  cost  of  material  and  making. 

The  average  cost  of  harvesting  (knocking,  gathering,  and  deliver- 
ing to  the  huller)  is  about  three  cents  a  pound,  and  the  cost  of  hulling 
and  drying  about  two  cents  a  pound.  The  harvesting  costs  vary 
greatly,  largely  according  to  the  size  of  the  crop.  The  smaller  the 
crop  the  greater  the  proportionate  cost. 

The  cost  of  orchard  operations  varies  with  the  prevailing  wages. 
Cultivation,  including  plowing,  probably  costs  $15  an  acre;  spraying 
about  $10  an  acre;  pruning  and  burning  brush,  about  $7;  and  irri- 
gating, if  practiced,  about  $8  an  acre. 

To  these  costs  must  be  added  taxes,  insurance,  upkeep  of  tools, 
depreciation  on  equipment  and  buildings,  cost  of  feed,  and  interest 
on  the  investment. 

Yields. — The  yield  of  almonds  in  different  years  and  in  different 
orchards  is  probably  more  variable  than  that  of  any  other  of  the 
common  orchard  fruits.  While  the  fluctuations  from  year  to  year 
are  largely  due  to  climatic  conditions,  the  variations  in  orchards  are 
due  largely  to  variety,  care  given  the  trees,  character  of  soil,  and  frost 
conditions. 

Almonds  begin  bearing  at  from  two  to  four  years,  the  first  crop 
ranging  from  one  or  two  nuts  up  to  a  hatful,  or  possibly  more.  At 
three  to  five  years,  they  should  yield  a  crop  which  will  pay  for  har- 
vesting. Ordinarily,  the  first  crop  that  it  will  pay  to  harvest  is  not 
obtained  until  near  the  latter  age,  though  this  depends  upon  the  type 
of  soil  in  which  the  trees  are  growing  and  the  moisture  conditions 
surrounding  them.  On  the  hill  lands  the  trees  begin  to  mature  much 
earlier  than  in  the  rich  bottom  lands,  and  consequently  come  into 
bearing  earlier.  It  must  be  borne  in  mind  that  a  crop  which  it  will 
pay  to  harvest  does  not  necessarily  mean  a  paying  crop.  It  does  not 
become  a  "paying  crop"  until  it  covers  the  cost  of  maintenance  as 
well  as  of  harvesting  and  handling.  Almond  orchards,  as  a  rule, 
reach  this  point  in  from  five  to  seven  years.  From  this  time  the  trees 
should  continue  to  increase  in  production  from  year  to  year,  allowing 
for  failures  due  to  frost  and  unfavorable  conditions,  until  they  are 
from  twelve  to  twenty  years  old.  Under  the  common  methods  of  care 
that  most  orchards  receive,  the  trees  begin  decreasing  in  production 
after  twenty-five  to  thirty  years,  and  in  some  cases  earlier.  On  the 
other  hand,  orchards  that  are  well  cared-for  often  continue  their 
maximum  production  even  longer.  The  age  at  which  an  orchard  will 
not  longer  pay  ranges  from  thirty  years  upward.  The  limit  is  still 
unknown. 


Circ.  284] 


THE  ALMOND  IN   CALIFORNIA 


37 


Investigations  carried  on  during  1913-1 412  brought  out  the  follow- 
ing facts :  The  average  production  of  almonds  in  California  is  between 
700  and  800  pounds  per  acre ;  if  care  is  exercised  in  the  selection  of 
a  proper  location  for  an  orchard  and  if  good  judgment  is  used  in 
managing  it,  1000  pounds  per  acre  would  be  a  safe  estimate  for 
business  purposes;  in  many  years  competent  orchardists  may  expect 
to  obtain  1500  pounds  per  acre,  but  this  would  not  be  likely  for  a 
ten-year  average.  The  possibilities  are  indicated  by  the  crop  from 
one  acre,  on  the  University  Farm  at  Davis,  California,  of  ten-year-old 
trees  which  produced  nearly  2800  pounds  in  1917. 


TABLE  3 

Net  Prices   (in  Cents  per  Pound)  Realized  by  the  Exchange  Members  for 

Different  Varieties  for  the  Years  1910  to  1923,  Inclusive 


Year 

Nonpareil 

I.  X.  L. 

Ne  Plus  Ultra 

Drake 

1910 

14.00 
16.50 
13.25 
17.25 
18.00 
13.00 
17.25 
17.50 
24.00 
26.00 
18.50 
18.00 
20.00 
15.00 

13.00 
15.50 
12.25 
16.25 
15.00 
12.00 
14.75 
16.00 
22.00 
24.00 
18.50 
17.00 
18.00 
13.00 

12.00 
14.50 

11.25 
15.25 
14.50 
11.00 
13.75 
15.00 
21.00 
21.00 
16.50 
16.00 
16.00 
13.00 

10.00 

1911 

12.00 

1912 

9.50 

1913 

13.25 

1914 

11.50 

1915 

9.25 

1916 

13.00 

1917 

12.50 

1918 

17.00 

1919 

14.00 

1920 

9.00 

1921 

9.00 

1922 

11.00 

1923 , 

8.00 

Average 

17.73 

16.23 

15.05 

11.36 

Returns. — Prices  paid  to  growers  have  fluctuated  considerably  on 
account  of  the  great  variation  in  both  the  Californian  and  European 
crops  from  year  to  year.  Table  3  shows  the  average  price  paid  to  the 
growers  for  the  four  principal  varieties  marketed  through  the  Almond 
Growers'  Exchange  since  its  organization. 

Table  4  shows  the  average  price  per  pound  paid  to  the  growers 
for  all  almonds  (unshelled),  including  all  qualities  and  the  entire  crop 
handled  by  the  Exchange  during  the  years  1910  to  1923  inclusive. 

From  these  figures  it  has  been  found  that  the  average  return  per 
pound  for  all  varieties  for  fourteen  years  based  on  the  crop  tonnage 


12  California  Agr.  Exp.  Sta.,  Cir.  121,  1914. 


38 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


for  each  year,  1910  to  1923,  inclusive,  was  13.98  cents.  It  is  interest- 
ing to  note  that  the  1923  crop  is  the  largest  produced  in  the  state  and 
also  that  the  average  price  paid  growers  is  practically  three  cents  less 
than  the  average  for  the  fourteen  years. 

TABLE  4 

Average  Prices  per  Pound  Paid  Growers  for  all  Unshelled  Almonds  for  the 
Years  1910  to  1923,  Inclusive 


Year 

Price  per  Pound, 

Cents 

California  Crop, 
Tons 

1910 

12.00 
13.50 
11.00 
15.50 
14.05 
10.75 
13.97 
14.23 
19.81 
19.01 
13.48 
13.40 
14.06 
10.98* 

3,300 

1911...               

1,450 

1912 

3,000 
1,100 
2,250 

1913 , 

1914 

1915...              

3,500 
3,400 

1916 

1917 

4,000 

1918 

5,100 

1919  ..             

7,250 

1920 

5,500 

1921                             

5,500 

1922 

8,500 

1923 

11,000 

Average  . 

13.98 

4,632 

Estimated. 


ALMOND  DISEASES  AND  PESTS  AND  THEIR  CONTROL 

DISEASES 

Crown-Gall. — This  disease,  which  is  also  known  as  root-knot  or 
black-knot,  is  one  of  the  most  serious  with  which  the  grower  has  to 
contend.  It  is  found  practically  everywhere  that  almonds  are  grown, 
and  either  greatly  reduces  the  vitality  of  the  trees  affected,  or  kills 
them,  according  to  the  seriousness  of  the  attack.  The  name  "root- 
knot"  is  more  commonly  applied  to  root  swellings  caused  by  nema- 
todes. 

Crown-gall  is  caused  by  a  bacterial  organism,  Bacterium  tume- 
faciens  S.  &  T.,  that  seems  to  be  native  to  most  California  soils.  It 
is  characterized  by  large  swellings  on  the  root  crown  or  main  roots 
just  below  the  surface  of  the  ground,  though  milder  infections  may 
sometimes  be  found  also  on  the  smaller  roots.     When  cut  open,  the 


CIRC.  284]  THE  ALMOND  IN   CALIFORNIA  39 

knots  appear  spongy  as  if  the  bark  and  wood  were  mixed  together  in 
one  mass.     They  are  most  serious  when  spread  over  a  large  surface, 
either  partially  or  completely  girdling  the  root  or  crown  of  the  tree. 
Control  methods  are  of  two  kinds : 

(1)  Nothing  but  clean,  healthy  nursery  trees,  free  from  all  trace 
of  galls,  should  be  planted.  All  broken  or  injured  roots  should  be 
carefully  trimmed  off,  leaving  nothing  but  smooth,  clean  cut  ends 
which  will  heal  over  readily  with  the  minimum  opportunity  for  infec- 
tion. 

(2)  Galls  on  orchard  trees  may  be  cut  out  to  clean,  healthy  wood 
with  a  sharp  knife  or  gouge  chisel.  The  wound  should  be  thoroughly 
disinfected  with  a  strong  (5  to  10  per  cent)  copper-sulfate  solution 
or  a  mixture  of  corrosive  sublimate  and  mercury  cyanide,  1  part  of 
each  to  500  parts  of  water  by  weight,  and  painted  when  the  surface 
is  dry  with  a  protective  covering  such  as  a  lead  and  oil  paint  or 
melted  asphaltum,  or  it  may  be  covered  directly  with  Bordeaux  paste. 
The  earth  should  be  replaced  over  the  roots.  The  trees  must  be 
reinspected  carefully  and  any  new  galls  which  have  formed  at  the 
wound  margin  removed  and  the  new  cuts  disinfected. 

The  use  of  resistant  stocks  has  been  suggested  as  a  means  of  avoid- 
ing infection,  but  no  such  stock  suitable  for  the  almond  has  yet  proved 
to  be  sufficiently  resistant  under  average  conditions  to  be  safely  recom- 
mended. The  greatest  hopes  for  future  success  in  combating  this 
disease,  however,  lie  in  this  direction. 

Oak  Fungus. — This  is  one  of  the  most  difficult  diseases  to  control 
because  it  works  and  spreads  beneath  the  surface  of  the  ground  in 
the  roots  of  trees.    In  some  sections  of  the  state  it  is  very  serious. 

The  disease,  often  called  root-rot,  is  caused  by  a  fungus,  Ar miliaria 
mellea,  commonly  called  "toadstool"  fungus.  It  is  known  as  oak 
fungus  because  the  disease  is  most  commonly  found  on  land  where  old 
oak  trees  have  stood.  Where  orchards  have  been  planted  on  such 
land,  spots  appear  in  which  the  trees  gradually  die,  the  disease  spread- 
ing from  tree  to  tree,  in  ever-widening  circles  which  take  in  ordinarily 
about  one  row  of  trees  each  year.  During  the  winter,  clusters  of 
toadstools  may  be  seen  at  the  base  of  the  affected  trees.  The  fungus 
lives  over  in  the  old  oak  roots  for  many  years  and,  as  the  orchard 
becomes  well  established,  spreads  to  the  almond  roots.  If  not  checked, 
the  spot  will  eventually  involve  the  entire  orchard  and  prevent 
further  growth  of  almonds  on  the  land  for  many  years. 

The  only  remedy  known  is  to  construct  barriers  around  diseased 
spots,  and  thus  prevent  the  infection  from  passing  beyond  through 


40  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

the  roots.  The  spread  of  the  disease  may  sometimes  be  held  in  cheek 
by  grubbing  out  a  row  or  two  of  healthy  trees  outside  the  affected 
area  and  taking  care  that  all  of  the  large  roots  are  removed  to  a  depth 
of  several  feet. 

There  are  no  resistant  stocks  known  at  present  upon  which  the 
almond  can  be  worked,  but  the  fig,  pear  on  French  stock,  and  walnut 
on  Northern  California  Black  Walnut  stock  may  safely  replace  the 
almond  in  affected  spots. 

Shot-hole  Disease. — There  are  three  different  fungi  that  produce 
the  shot-hole  effect  on  the  leaves  of  the  almond. 

(1)  Coryneum  beijerinckii  Oud,  or  peach  blight,  is  the  most  com- 
mon form.  It  is  not  so  serious  on  the  wood  of  the  almond  as  it  is  on 
that  of  the  peach,  but  in  seasons  of  damp  spring  weather  it  does 
much  damage  to  the  blossoms,  fruits,  and  leaves.  Affected  blossoms 
are  killed  outright,  the  flowers  turning  brown  and  dropping  much 
as  if  killed  by  frost.  The  young  fruit  is  spotted  by  the  fungus,  which 
causes  malformation,  gumming,  and  shriveling  of  the  nuts,  varying 
with  the  severity  of  the  attack.  On  the  leaves  many  small  dead  spots 
appear,  the  dead  tissue  soon  falling  out  and  giving  the  shot-hole  effect. 
Where  the  twigs  are  affected,  small  dead  spots  appear  during  the 
the  winter,  most  often  at  the  buds.  This  causes  the  death  of  the  buds 
and  often  the  ends  of  the  twigs,  During  the  spring,  after  growth 
starts,  gumming  occurs  at  these  spots. 

Only  two  sprays  are  known  to  give  effective  control — Bordeaux 
mixture  and  lime-sulphur  (winter  strength).  One  or  the  other  should 
be  given  in  the  fall,  as  soon  as  the  trees  become  dormant,  and  again 
just  before  the  buds  open  in  the  spring.  Both  the  fall  and  the  spring 
sprays  must  be  thoroughly  applied  to  be  effective. 

(2)  Cercospora  circumscissa  Sacc.  is  another  fungus  causing 
much  the  same  effect  as  the  Coryneum.  It  is  difficult  for  an  un- 
trained person  to  distinguish  between  them.  The  same  sprays  used 
for  Coryneum  are  effective  in  controlling  the  'cercospora,  though  if 
this  form  alone  is  present  the  spring  spraying  alone  should  be 
sufficient. 

(3)  Gloeosporium  amygdalinum  Brizi,  while  apparently  uncom- 
mon in  this  state,  has  been  found  to  exist  in  some  places.  Its  behavior 
and  the  most  satisfactory  methods  of  control  are  not  exactly  known, 
but  it  is  believed  that  the  control  measures  mentioned  for  the  other 
forms  of  ''shot-hole"  are  also  applicable  to  this. 

Brown  Rot  (Sclerotina  cinerea  Wor.)  is  a  fungous  disease  which 
attacks  all  stone  fruits  including  almonds.    The  flowers  are  susceptible 


CIRC.  284]  THE  ALMOND  IN   CALIFORNIA  41 

when  the  petals  show  in  the  buds  and  remain  so  until  the  "jackets" 
(calyx  and  other  flower  parts)  are  shed  from  the  fruit.  The  fungus 
grows  down  through  the  fruit  into  the  twig.  The  inner  bark  turns 
brown,  and  copious  amber  gumming  generally  occurs.  Long  shoots 
may  thus  be  killed  by  girdling.  The  fungus  remains  alive  in  the  dead 
twigs  which  serve  as  a  source  of  infection  the  following  spring.  The 
disease  is  rarely  serious  except  near  the  coast  and  then  only  in  seasons 
when  wet  weather  comes  at  the  critical  time. 

During  the  fall  all  dead  twigs  should  be  cut  out  and  destroyed. 
Where  the  disease  is  serious,  a  Bordeaux  8-8-50  or  a  lime-sulfur  1-10 
spray  should  be  applied  during  the  bud  stage  as  the  petals  are  show- 
ing. (Lime-sulfur  is  preferable,  especially  when  the  twig  borer  and 
almond  mite  eggs  are  present.) 

Prune  Bust  (Puccinia  Pruni  Pers.). — This  fungus  is  worst  in  the 
southern  coast  sections  where  almonds  are  not  extensively  grown. 
It  is  not  serious  on  thrifty  trees  well  supplied  with  moisture.  It  is 
characterized  by  reddish  pustules  on  the  under  sides  of  the  leaves, 
appearing  generally  about  July  or  August  and  causing  a  premature 
yellowing  and  dropping  of  the  leaves.  No  method  of  control  is 
known. 

Heart  Rot. — This  is  one  of  the  most  insidious  of  tree  diseases,  for 
it  works  inside  beneath  an  apparently  healthy  exterior  until  the  decay 
has  progressed  so  far  that  the  tree  commences  to  break  down,  and 
then  it  is  too  late  for  remedial  measures.  The  almond  is  not  so 
susceptible  to  this  as  most  other  kinds  of  orchard  trees,  but  where 
large  wounds  have  been  exposed  to  the  weather,  infection  may  take 
place  readily ;  and  after  it  is  once  well  started,  it  continues  at  a  com- 
paratively rapid  rate.  Decay  is  caused  in  most  cases  by  one  or  more 
of  about  a  dozen  different  fungi,  of  which  the  oyster-shell  fungus  is 
by  far  the  most  common. 

Control  consists  in  taking  care  to  leave  no  open  wounds  exposed 
to  the  air  to  dry  and  crack  and  thus  permit  the  entrance  of  decay 
organisms.  Much  of  this  can  be  avoided  by  care  in  pruning  the  young 
tree  so  that  the  removal  of  the  large  limbs  will  not  be  necessary  later 
on.  Where  such  wounds  must  be  made,  measures  should  be  taken 
to  prevent  infection.  This  can  be  done  best  by  making  smooth,  clean 
cuts  close  to  the  part  from  which  the  branch  arises.  Such  cuts  heal 
over  more  quickly  than  stubs  which  dry  and  crack  and  sometimes  do 
not  heal  over  at  all.  All  such  wounds  which  do  not  heal  over  the 
first  season  should  be  covered  with  some  good  disinfectant,  such  as 
corrosive  sublimate,  1  part  to  1000  parts  of  water,  or  Bordeaux  paste. 


42  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

When  well  dried  the  wound  should  be  painted  over  with  some  elastic 
coating,  such  as  "Flotine,"  grade  D  asphaltum,  or  a  good  white  lead 
paint  applied  with  a  brush.  The  entire  wound  must  be  covered  or 
the  work  is  largely  wasted. 

Die-back. — This  is  often  serious  in  orchards  where  the  moisture 
is  insufficient  to  carry  the  trees  through  the  growing  season.  Unfavor- 
able soil  conditions,  such  as  hardpan,  gravel  or  sand,  may  be  the 
direct  cause  of  such  moisture  shortage.  Lack  of  soil  fertility  is  also 
a  common  cause.  Control  measures  consist  in  remedying  the  defective 
conditions.  Where  this  cannot  be  done  economically,  it  is  better  to 
abandon  further  attempts  at  almond  culture  on  such  land. 

Sour-sap. — This  is  one  of  the  so-called  "physiological  diseases " 
and  is  quite  common  in  the  almond.  It  is  most  frequently  found 
where  trees  are  planted  in  heavy  or  poorly  drained  soils.  The  fact 
that  the  almond  cannot  endure  standing  water  around  its  roots  for 
any  length  of  time,  particularly  after  growth  commences  in  the  spring, 
renders  it  especially  liable  to  soursap  in  soils  where  excess  water  from 
the  late  winter  and  spring  rains  cannot  be  readily  drained  away. 
Sudden  changes  in  weather  from  warm  to  cold  after  growth  com- 
mences are  the  direct  cause  of  the  trouble.  The  flow  of  sap  is  checked 
very  suddenly  and  stagnation,  cracking  of  the  bark,  and  fermentation 
ensue.  With  an  unusually  strong  flow  of  sap  in  trees  in  wet  soils, 
such  climatic  changes  cause  unusually  severe  disturbance  in  the 
normal  functioning  of  the  trees. 

The  affected  trees  ordinarily  show  the  disease  first  in  the  spring, 
when  gum  may  be  seen  oozing  from  the  bark  of  the  trunk  or  main 
branches,  and  sometimes  even  from  the  smaller  ones.  Small  or  large 
branches,  and  in  severe  cases,  the  whole  tree,  may  die  soon  after  begin- 
ning to  leaf  out  strongly.  When  the  bark  is  cut  through  to  the  wood 
and  peeled  back  a  strong  sour  odor  is  noticeable.  The  cambium 
layer  appears  brownish  or  reddish  in  color,  and  often  masses  of  gum 
are  found  between  the  bark  and  the  wood.  Mild  cases  may  not  be 
serious  enough  to  show  on  the  outside  of  the  tree  and  only  portions 
of  the  cambium  layer  may  die.  The  sudden  dropping  of  the  blossoms 
or  young  fruit  may  in  some  instances  be  attributable  to  sour-sap. 

All  affected  parts  on  smaller  branches  should  be  cut  back  to 
healthy  wood,  while  on  the  main  branches  or  trunk,  where  only  a 
small  portion  or  one  side  is  affected,  it  is  best  to  clean  out  the  dead 
bark  and  paint  the  bared  wood  with  a  protective  covering  until  new 
bark  can  cover  the  spot.  At  the  same  time,  every  effort  should  be 
made  to  remedy  the  soil  moisture  conditions  which  were  largely 
responsible  for  the  trouble  in  the  first  place. 


CIRC.  284]  THE  ALMOND  IN   CALIFORNIA  43 

Fruit-drop. — The  same  conditions  which  cause  sour-sap  may  cause 
fruit  drop.  Lack  of  pollination  due  to  improper  mixing  of  varieties 
or  to  rain  during  the  blossoming  may  be  another  cause.  Frost  may 
also  produce  the  same  thing  by  killing  the  germ  in  the  young  fruit. 
In  such  cases,  the  fruit  may  not  fall  from  the  tree  for  one  or  two 
weeks  after  the  injury  occurs,  and  in  some  instances,  may  even  appear 
to  continue  its  development  for  a  short  while. 


INSECT  PESTS 

Mites. — Commonly  called  red  spiders.13  There  are  three  kinds  of 
mites  that  do  much  damage  in  almond  orchards,  the  brown  or  almond 
mite,  the  common  red  spider  or  two-spotted  mite,  and  the  European 
red  mite.14  These  are  common  in  all  parts  of  the  state  and  the  first 
two  are  the  worst  pests  the  almond  grower  has  to  face. 

The  brown  mite  (Bryobia  praetiosa  Koch),  which  does  not  spin 
a  web,  is  dark  red  or  brown  in  the  adult  stage,  has  very  long  front 
legs,  and  a  flattened  back.  It  works  on  the  green  bark  of  the  small 
twigs  as  well  as  on  the  leaves,  sucking  the  plant  juices  from  beneath 
the  bark.  The  leaves  become  mottled  and  eventually  fall,  although 
not  to  such  an  extent  as  when  attacked  by  the  two-spotted  mite.  The 
injury  to  the  tree  is  just  as  great  because  of  the  serious  drain  on  its 
vitality  and  because  of  the  earliness  of  the  attack,  most  of  the  injury 
being  done  in  the  spring  and  early  summer.  This  mite  may  spend  its 
entire  life  on  the  tree ;  the  very  small,  round,  red  eggs  being  laid  most 
often  on  the  under-side  of  the  branches  and  in  cracks  and  crevices 
in  the  bark  and  twigs.  These  remain  on  the  tree  throughout  the 
winter  and  hatch  early  in  the  spring  soon  after  the  trees  have  their 
leaves  half  developed,  leaving  the  white  egg-shells  in  place. 

The  brown  mite  may  be  controlled  satisfactorily  in  the  egg  stage 
by  means  of  a  dormant  spray  of  lime-sulfur  solution,  one  gallon  to 
nine  gallons  of  water,  applied  just  before  the  buds  open  in  the  spring. 
Crude  oil  emulsion  as  a  dormant  spray  is  also  effective,  if  thoroughly 
applied  over  the  entire  tree  under  high  pressure.  The  lime-sulfur 
spray  should  be  used  in  the  same  way. 

During  the  growing  season  a  milder  material  must  be  used.  Dry 
dust  sulfur,  using  only  the  very  finest  grade  of  ''flowers  of  sulfur," 
is  often  very  effective,  provided  weather  conditions  are  satisfactory. 
It  must  generally  be  applied  several  times,  however,  if  the  best  results 


13  See  also  California  Agr.  Exp.  Sta.,  Bull.  347,  1922. 

14  Formerly  called  the  citrus  mite. 


44  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

are  to  be  obtained.  The  work  is  done  by  blowing  the  sulfur  dust  into 
the  tree  with  blowers  in  the  early  morning  when  there  is  little  or  no 
wind. 

A  more  satisfactory  method  is  to  use  5  pounds  of  sulfur,  %  pound 
of  casein  spreader,  and  2  gallons  of  liquid  lime-sulfur  to  100  gallons 
of  water  in  cases  where  no  winter  treatment  has  been  used,  or  where 
there  are  no  serious  attacks  of  either  of  the  other  two  species  of  red 
spiders. 

The  common  red  spider  or  two-spotted  mite  (Tetranychus  telarius 
Linn)  is  of  a  pale  yellow  color  with  occasionally  a  reddish  tinge  and 
sometimes  two  darker  spots  on  either  side  of  the  body.  It  is  a  web- 
spinning  species.  Unlike  the  brown  mite,  it  spends  the  winter  and 
early  spring  on  weeds  and  hardy  cultivated  plants.  During  the  warm 
days  of  early  summer,  generally  in  June,  the  mite  makes  its  appear- 
ance on  the  trees,  spinning  a  fine  web  on  the  leaves,  generally  on  the 
upper  surface,  and  then  working  under  this  web.  The  mite  sucks  the 
plant  juices  from  the  leaves,  giving  them  a  yellowish  mottled  appear- 
ance. These  leaves  soon  die  and  drop  to  the  ground.  In  serious 
infestations  the  trees  are  often  almost  completely  defoliated  by  the 
end  of  August  (see  fig.  13). 

The  use  of  dormant  sprays  is  not  effective  for  controlling  the 
yellow  mite,  but  the  summer  sprays  mentioned  above  are  all  satis- 
factory, and  for  the  best  results  must  be  applied  under  high  pressure, 
preferably  200  pounds  or  more. 

The  citrus  mite  (Paratetranychus  pilosus  Can  &  Tanz)  spins  a 
web,  but  is  generally  less  abundant  on  almonds  than  either  the  brown 
or  the  two-spotted  mite.  The  life-history  of  this  mite  is  similar  to 
that  of  the  brown  mite  in  that  the  winter  is  spent  in  the  egg  stage 
on  the  host  of  the  previous  summer. 

This  mite  is  of  a  deep  red  color  and  is  much  smaller  than  the 
almond  mite.  It  is  almost  too  small  to  be  seen  with  the  unaided  eye. 
The  sprays  mentioned  above  will  control  the  citrus  mite. 

Peach  Twig  Borer15  (Anarsia  lineatella  Zeller). — In  the  larval 
stage  these  borers  work  on  the  young  buds,  shoots,  and  fruits.  In  the 
early  spring  they  are  especially  troublesome  in  newly  planted  orchard 
trees  when  a  comparatively  small  number  may  kill  most  of  the  new 
shoots  which  are  needed  to  make  the  desired  framework  of  the  tree. 
In  some  years  they  may  be  serious  in  large  trees  also.  Dormant  spray 
of  lime-sulfur,  1-10,  applied  under  high  pressure  just  as  the  buds  are 
opening  in  the  spring  will  generally  control  the  borers.     However,  in 


is  See  also  California  Agr.  Exp.  Sta.,  Bull.  355,  1923. 


CIRC  284] 


THE  ALMOND  IN   CALIFORNIA 


45 


Fig.  13. — Nonpareil  almonds.  Branch  on  left  free  from  Red  Spider  and 
holding  its  full  supply  of  leaves  in  green,  healthy  condition;  branch  on  right 
defoliated  by  Two-spotted  mite.  Note  premature  ripening  of  nuts  on  defoliated 
branch. 


46  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

serious  infections  the  addition  of  three  pounds  of  basic  arsenate  of 
lead  to  every  100  gallons  of  spray  is  advisable.  This  same  spray  may 
be  used  to  control  the  brown  mite,  thereby  accomplishing  double 
control. 

California  Peach  Borer  (Aegeria  opalescens  Hy.  Edw.). — The 
larvae  are  serious  in  many  parts  of  the  state  where  they  burrow  just 
under  the  bark  near  the  surface  of  the  ground.  They  may  be  detected 
by  the  small  bits  of  frass  and  gum  at  the  entrance  to  their  burrows. 
If  allowed  to  continue,  they  will  eventually  girdle  the  tree. 

The  surest  means  of  control  is  to  dig  out  the  worms  with  a  knife 
or  to  kill  them  with  a  wire  probe.  This  work  should  be  done  system- 
atically in  the  fall  and  spring  and  the  wounds  painted  with  a  good 
asphalt  paint.    Use  para-clichlorobenzine  in  summer  and  fall.16 

Thrips  (Taeniothrips  inconsequens  Uzel.). — These  are  most  serious 
on  the  almond  leaves,  their  attacks  sometimes  causing  considerable 
defoliation  in  late  spring  or  early  summer.  They  may  be  controlled 
by  spraying  with  distillate,  to  which  has  been  added  ' '  Black  Leaf  40 ' ' 
(40  per  cent  nicotine)  at  the  rate  of  1  part  to  1500  parts  of  water  or 
other  spray  mixtures.  It  is  possible  that  some  insects  other  than  the 
pear  thrips  do  similar  damage,  but  the  spray  described  above  should 
be  effective  against  all. 

Scale,  aphis,  diabrotica,  and  other  insects  are  sometimes  found  on 
the  trees,  but  are  generally  not  sufficiently  troublesome  to  require 
special  attention.  Most  of  them  are  held  in  check  by  the  control 
measures  used  for  the  more  serious  pests. 

Indian  Meal  Moth  (Plodia  inter punctella  Hln.). — The  larva  of 
this  moth  feeds  on  the  kernels  of  the  harvested  almonds  after  they 
are  stored.  Infestation  usually  takes  place  in  storerooms  or  ware- 
houses in  which  the  nuts  have  been  placed  for  a  time.  The  ware- 
houses become  infested  from  old  grain  bags  which  have  been  kept 
there  previously.  So  far  as  known,  infestation  does  not  take  place  in 
the  field.  The  larvae  continue  to  work  in  the  stored  almonds  for  a 
long  time,  doing  a  great  amount  of  damage.  They  may  be  controlled 
by  thoroughly  cleaning  out  the  corners  of  the  warehouse  and 
thoroughly  disinfecting.  The  nuts  should  be  disinfected  with  carbon 
bisulphide  (explosive  when  in  the  form  of  a  gas  mixed  with  air),  or 
by  other  means  used  to  control  insects  in  grain.  Prevention  is  far 
easier  than  cure  in  this  case. 


16  See  also  California  Agr.  Exp.  Sta.  Cir.  265,  1923. 


CIRC.  284]  THE  ALM0ND  IN   CALIFORNIA  47 


SPEAY  PEOGEAM 

Under  most  conditions  the  following  spray  program  is  recom- 
mended : 

First  Application. 

In  late  winter  before  the  buds  open,  with  commercial  lime-sulfur, 
winter  strength,  for  almond  shot-hole  fungus,  brown  mite  (red  spider) 
eggs,  moss  and  lichens  and  soft-bodied  insects.  Crude  oil  emulsion  is 
more  effective  against  red  spider  eggs  than  is  lime-sulfur  solution. 

Second  Application. 

In  summer  when  two-spotted  mite  (red  spider)  appears,  about 
June  1 : 

Flowers  of  sulphur — 5  pounds. 

Casein  spreader — %  pound. 

Liquid  lime-sulfur — 2  gallons. 

Water  to  make — 100  gallons. 

Spray  early,  before  red  spider  become  numerous  and  as  often  as 
necessary. 

Additions  or  Modifications. 

In  certain  sections  where  shot-hole  fungus  is  serious  a  fall  appli- 
cation of  Bordeaux  mixture  is  recommended. 

Where  the  peach  twig  borer  is  serious  it  is  advisable  to  delay  the 
late  winter  lime-sulfur  spray  and  add  3  pounds  of  basic  arsenate  of 
lead  powder  per  100  gallons  of  solution. 

OTHEE  PESTS 

Grasshoppers. — Grasshoppers  have  been  serious  in  orchards  in 
outlying  foothill  districts  in  some  years,  and  especially  in  young 
orchards,  making  it  almost  impossible  to  get  trees  started  properly. 
In  such  locations  special  means  must  be  employed  on  a  large  scale  to 
protect  orchards  from  their  devastations.  Of  these  poisoned  bait  and 
hopper  dozers  are  the  most  effective. 

Gophers. — These  often  do  great  damage  to  the  trees  by  girdling 
just  below  the  surface  of  the  ground.  Even  if  they  do  not  actually 
girdle  the  trees,  the  injury  may  be  sufficient  to  devitalize  the  tree ; 
in  addition,  the  wounds  made  by  their  gnawings  frequently  become 
infected  with  crown-gall.  The  only  safe  means  of  control  known  is 
the  constant  use  of  traps  supplemented  by  poisoned  bait. 


48  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

Squirrels. — Squirrels  are  very  troublesome,  as  they  harvest  a  large 
amount  of  almonds  before  they  are  sufficiently  ripe  to  be  harvested  by 
the  grower.  The  use  of  poisoned  grain  or  "gas,"  if  used  over  a 
large  area  of  surrounding  territory,  will  prevent  serious  depredations. 

Birds. — Birds  also  carry  off  large  amounts  of  almonds  if  the 
orchards  are  near  open  country  or  hills,  especially  if  wooded.  Crows, 
bluejays,  blackbirds,  yellow-hammers,  robins,  and  others  are  the 
worst  offenders.  Sometimes  linnets  eat  off  large  numbers  of  fruit- 
buds  in  the  spring  in  some  of  the  newer  sections  where  plantings  are 
scattered.  Sap-suckers  have  been  known  to  girdle  entire  trees  or 
large  branches  by  boring  holes  around  the  trunk  or  limbs.  Generally 
the  damage  from  birds  does  not  warrant  any  control  measures. 

Morning -Glory. — This  is  probably  the  worst  of  the  weeds  of 
almond  orchards,  and  is  the  hardest  to  control.  Sheep  and  chickens 
may  be  used  with  excellent  results,  provided  care  is  taken  to  see  that 
the  sheep  are  not  allowed  to  go  hungry,  for  then  they  will  bark  the 
trunks  of  the  trees  very  quickly.  An  excellent  plan  is  to  arrange 
gates  so  that  the  sheep  must  go  through  the  orchard  from  pasture  to 
get  water.  In  passing  back  and  forth  they  will  forage  over  the  entire 
orchard  and  dig  up  all  the  morning-glory  in  sight.  Chickens  are 
fond  of  the  succulent  new  shoots,  and  will  keep  them  below  the  ground 
until  the  underground  stems  and  roots  weaken  and  die.  Cultivation 
throughout  the  growing  season,  often  enough  to  prevent  the  morning- 
glory  from  developing  any  leaves  for  a  whole  year  at  least,  and  longer 
if  necessary,  will  starve  the  plants  to  death. 


VARIETIES17 

In  selecting  varieties  of  almonds  for  planting  in  California  the 
grower  should  choose  those  that  are  most  marketable  and  that  at  the 
same  time  secure  the  best  results  in  cross-pollination.  At  the  present 
time  there  are  comparatively  few  varieties  of  almonds  which  have 
won  and  retained  their  popularity  with  both  the  grower  and  the 
trade.  There  are  a  number  of  reasons  for  this  condition.  The  cul- 
tural, climatic,  and  soil  conditions  under  which  the  almond  thrives 
are  much  more  limited  than  for  most  of  the  common  deciduous  fruits ; 
the  area  of  production  in  America  is  limited  largely  to  California ;  the 
industry  is  comparatively  new,  and  in  general,  there  is  not  the  great 


17  Detailed    description    of  varieties  may  be   found   in   "Almond   Varieties  in 
the  United  States,  U.  S.  D.  A.,  Dept.  Bull.  1282,  1924. 


ClBC.  284]  THE  ALMOND  IN   CALIFORNIA  49 

varietal  variation  in  season,  appearance,  texture,  flavor,  and  behavior 
that  is  found  in  the  apple,  peach,  pear,  and  similar  fruits.  With 
almonds,  the  season  of  all  varieties  extends  from  one  harvest  to  the 
next,  if  properly  handled.  Growers  are,  therefore,  recommended  to 
plant  only  standard,  marketable  varieties  so  far  as  possible. 

Early  ripening  varieties  are  best.  The  crop  should  be  in  the 
hands  of  the  trade  early,  for  the  bulk  of  it  is  used  in  the  holiday 
trade.  This  is  especially  true  of  unshelled  almonds.  Moreover,  only 
early  almonds  can  be  harvested  and  sold  before  the  bulk  of  the  Euro- 
pean shipments  arrive. 

The  same  variety  often  ripens  at  slightly  different  times  in  differ- 
ent seasons,  in  different  sections  and  even  in  different  orchards  in 
the  same  season.  Generally,  harvesting  commences  early  in  August 
and  closes  about  the  middle  of  October.  The  approximate  order  in 
which  the  better  known  varieties  ripen  is  shown  in  table  5. 

TABLE  5 
Approximate  Order  of  Ripening  of  Varieties  of  Almonds 


1.  Nonpareil 

4.  Peerless 

5.  Golden  State 

2.  I.  X.  L. 

Princess 

6.  Lewelling 

Eureka 

California 

7.  Drake 

Jordan 

King 

8.  Languedoc 

3.  Ne  Plus  Ultra 

Silver 

Texas 
9.  Reams 

Many  new  varieties  have  been  originated  in  California,  but  most 
of  them  have  fallen  into  disfavor  in  a  short  time.  In  fact,  it  is 
impossible  now  to  find  even  single  trees  of  some  varieties  which 
were  formerly  well  known.  From  time  to  time,  however,  worthy 
varieties  have  been  introduced  and  have  succeeded  in  making  a  per- 
manent place  for  themselves  through  their  ability  to  fill  a  demand  that 
before  had  been  but  partially  or  poorly  supplied. 

In  view  of  the  changing  market  situation  for  California  almonds, 
due  to  the  rapidly  increasing  acreage  and  to  the  very  limited  demand 
for  unshelled  almonds,  it  is  safe  to  predict  that  the  only  new  varieties 
which  will  be  of  value  in  the  future  will  be  those  that  are  primarily 
of  superior  quality  for  shelling  purposes.  Yield  must  take  second 
place. 

Well-known  varieties  are  not  only  in  greater  demand  in  the  prin- 
cipal markets,  but  they  invariably  bring  much  better  prices  than  the 
newer  varieties.     In  some  years,  when  the  domestic  crop  of  a  given 


50 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


variety  is  light  and  the  demand  good,  it  is  possible  to  unload  poorer 
or  less  known  varieties  at  fairly  good  prices.  More  often,  however, 
they  are  a  drug  on  the  market. 

All  varieties  will  vary  in  size  from  season  to  season  and  in  different 
orchards  during  the  same  season,  according  to  the  plant  food  and 
moisture  supply  available  during  the  time  the  nuts  are  maturing. 


i 


« ■"-'  * 


Fig.    14. — Typical   Nonpareil   almond  tree  in    University  Farm   orchard;    nine 
years  old.     Note  numerous  watersprouts  which  must  be  removed. 

Some  varieties,  notably  the  Nonpareil,  vary  more  in  size  than  in 
plumpness,  while  others,  like  the  Ne  Plus  Ultra,  are  more  inclined  to 
produce  somewhat  shriveled  kernels  and  imperfectly  developed  shells 
though  the  variation  in  size  will  not  be  so  great.  As  the  yields  become 
heavier,  the  nuts  are  likely  to  be  smaller.  Young,  vigorous  trees  with 
a  light  crop  often  produce  unusually  large  nuts  with  comparatively 
thin  shells.  The  value  of  a  variety,  therefore,  depends  largely  upon 
its  behavior  after  the  trees  reach  full  maturity  and  bearing. 


Circ.  284] 


THE  ALMOND  IN   CALIFORNIA 


51 


Varieties  Recommended. — The  best  marketable  nuts  are,  as  has 
been  suggested,  few  in  number,  and  most  of  these  do  well  in  all  of 
the  principal  almond  districts  of  California.  Where  the  climatic  and 
soil  conditions  are  favorable  there  is  no  great  difference  in  the  be- 
havior of  the  several  varieties,  but  where  these  conditions  are  not  so 
favorable  certain  varieties  do  better  than  others. 

The  Nonpareil  (fig.  14),  the  best  variety  known  at  the  present 
time  for  California  conditions,  bears  more  nearly  uniform  crops  from 
year  to  year  and  shows  a  wider  range  of  adaptation  than  any  of  the 


Fig.  15. — Typical  Drake  almond  tree  in  University  Farm  orchard;  nine  years  old. 

other  good  commercial  varieties.  It  has  proved  itself  to  be  satisfac- 
tory in  every  almond  district  in  the  state.  The  Drake  (fig.  15)  closely 
approaches  the  Nonpareil  in  this  respect.  The  I.  X.  L.  (fig.  16)  and 
Ne  Plus  Ultra  (fig.  17)  are  the  most  variable  in  their  behavior.  The 
blossoms  of  these  two  varieties  seem  to  be  more  tender  and  hence 
more  liable  to  injury  under  unfavorable  conditions ;  gumming  is  more 
prevalent  near  the  coast,  and  during  harvest  the  slower  ripening  and 
opening  of  the  hulls  in  the  more  moist  atmosphere  in  many  of  the  coast 
valleys  cause  excessive  darkening  and  sometimes  molding  of  the  shell. 
The  Ne  Plus  Ultra  does  best  on  comparatively  high,  well-drained  soils, 
adjacent  to  the  larger  streams  in  the  Sacramento  valley,  such  as  the 
lands  along  the  Sacramento  River,  Putah  Creek,  Cache  Creek,  etc. 
It  grows  and  produces  well  in  the  Banning  district  and  in  many  of 


52 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 


the  foothill  sections  where  conditions  are  favorable.  The  I.  X.  L. 
does  best  on  the  foothills  surrounding  the  Sacramento  Valley,  par- 
ticularly on  the  west  side.  Varieties  which  ripen  later  than  the  Drake 
should  be  avoided  in  the  Banning  district  and  other  sections  of 
similar  climatic  conditions  because  of  the  liability  to  damage  from  the 
frequent  October  rains. 


Hi 


Fig.  16. — Typical  I.  X.  L.  almond  tree  in  University  Farm  orchard;  nine  years  old. 

Doubtful  and  Undesirable  Varieties. — There  are  a  number  of 
different  varieties,  such  as  the  Eureka  and  Jordan  which  give  prom- 
ise of  filling  a  limited  place  in  the  markets,  but  which  have  not  yet 
been  thoroughly  tested  throughout  the  state.  It  is  still  a  question 
as  to  whether  growing  them  in  very  large  quantities  would  affect  the 
price.  The  Jordan  nut  is  of  excellent  quality,  but  in  California  the 
trees  are  variable  in  vigor.    In  some  cases  the  trees  make  unusually 


Circ.  284] 


THE  ALMOND   IN   CALIFORNIA 


53 


large,  vigorous  growth,  while  in  others  they  are  small  and  apparently 
stunted.  In  general,  the  Jordans  do  not  hear  sufficiently  heavy  crops 
to  make  them  pay  at  the  prevailing  low  [trices. 


... 


•■» 


w 


-  ~V 


Fig.  17. — Typical  No  Plus  Ultra  almond  tree  in  University  Farm  orchard:  nine 
years  old. 


Other  varieties,  such  as  the  Texas,  have  been  sufficiently  tested 
to  show  their  adaptability  to  most  districts,  but  they  are  not  recom- 
mended because  of  the  difficulty  experienced  in  marketing  them  at 
a  profit  in  large  quantities.     The  Texas  has  been  planted  extensively 


54  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION 

in  California  without  sufficient  justification.  It  was  planted  because 
of  its  value  as  a  pollinizer,  and  of  its  precocious  and  prolific  bearing. 
In  small  quantities  it  was  sold  in  less  exacting  markets  as  a  Drake, 
but  in  larger  quantities  the  trade  has  objected  to  it.  Its  lateness 
in  ripening  is  making  it  harder  each  year  satisfactorily  to  market 
the  rapidly  increasing  tonnage  of  this  variety.  It  should,  therefore, 
be  avoided  in  new  plantings. 

Unshelled  Almonds. — Athough  future  markets  will  no  doubt  use 
shelled  almonds  very  largely,  there  will  always  be  a  limited  demand 
for  unshelled  almonds  for  use  in  the  holiday  trade  and  for  home 
table  use.  Unshelled  almonds  for  such  purposes  must  be  large, 
attractive  nuts  with  light-colored,  clean-looking  shells,  soft  enough 
to  be  broken  with  the  hands.  The  kernels  must  be  well  filled  and  free 
from  gum.  The  I.  X.  L.  is  the  most  popular  and  highest  priced  nut 
for  these  purposes.  The  Ne  Plus  Ultra  ranks  next  because  of  its 
attractive  outside  appearance  and  shape,  one  of  the  principal  objec- 
tions to  it  being  its  tendency  to  have  gummy  kernels.  The  Drake  is 
another  variety  in  demand  by  the  holiday  trade.  It  is  moderately 
large,  plump,  and  well  filled  with  a  good  kernel  and  while  not  so 
attractive  as  the  I.  X.  L.  or  Ne  Plus  Ultra,  it  is  one  of  the  most 
popular  medium  priced  nuts.  A  certain  class  of  trade  prefers  the 
Nonpareil,  which  appears  to  be  growing  in  popularity  because  of  the 
attractive  kernel  and  the  ease  with  which  it  may  be  shelled  by  hand. 

Shelled  Almonds. — The  confectioners,  on  the  other  hand,  care 
nothing  for  the  shell.  They  want  a  medium  or  large  sized  kernel, 
uniform  in  shape,  and  plump ;  one  that  can  be  coated  smoothly  or 
evenly  with  candy.  For  blanching  and  salting  purposes,  the  kernels 
must  be  large  and  smooth.  The  best  California  variety  for  this  pur- 
pose is  the  Nonpareil.  It  is  also  the  best  nut  for  table  use  when  sold 
unshelled.  As  a  rule,  the  papershell  varieties  are  the  best  for  shell- 
ing because  of  the  large  percentage  of  unbroken  kernels  which  may 
be  obtained.  The  broken  kernels  and  those  obtained  from  cheaper  and 
less  desirable  varieties  are  used  largely  by  the  bakers  and  almond- 
paste  manufacturers. 

Owing  to  the  increasing  consumption  of  shelled  almonds  and  the 
probability  of  a  still  greater  increase  in  the  future,  growers  should 
arrange  future  plantings  with  a  view  to  supplying  the  best  shelling 
varieties.  At  the  present  time,  the  best  shelling  varieties  are  not 
ordinarily  the  heaviest  producers.  With  a  limited  production  they 
may  not  even  bring  as  large  returns  as  the  poorer  but  heavier  yield- 
ing varieties.     As  the  production  increases,  which  it  is  doing  very 


Circ.  284] 


THE  ALMOND  IN   CALIFORNIA 


55 


rapidly,  the  relative  value  of  the  best  shelling  varieties  will  increase 
in  proportion  and  bring  good  prices  when  it  will  be  impossible  to 
move  at  a  profit  a  heavy  tonnage  of  a  poor  variety. 

Size  of  Almonds — Per  Cent  of  Kernels  and  Per  Cent  of  Doubles. 
— Records  of  fourteen  varieties  of  almonds  grown  in  the  same 
orchard  under  similar  conditions  of  soil  and  culture  have  been  kept 
at  the  University  Farm  at  Davis,  for  the  years  1913  to  1916  inclusive. 
These  trees  are  all  of  the  same  age,  except  the  Texas,  Peerless,  and 
Harriott,  which  are  one  year  younger  than  the  others.  The  figures 
in  table  6  show  that  there  is  a  wide  variation  among  varieties,  as 
regards  not  only  the  size,  but  the  proportion  of  shell  to  the  whole 
nut,  and  the  proportion  of  double  kernels. 

TABLE  6 

Showing  Number  per  Pound,  Per  Cent  of  Kernels,  and  Proportion  of 

Double  Kernels 


Variety 

Nonpareil 

I.  X.  L 

Ne  Plus  Ultra 

Drake 

Languedoc 

Texas 

Reams 

Lewelling 

Peerless 

Princess 

California 

King 

Harriott 

Jordan 


Number  of  nuts 
per  pound 


236 
152 
167 
145.5 
211 
173 
140.5 
150 
124 
238 
216 
241 
167 
74 


Weight  per  cent 
of  kernels  to 
whole  nuts 


52.28 

56.45 

44.48 

49.16 

43.89 

45.27 

46.96 

36.05 

70.6 

70.43 

71.2 

53.68 

25.23 


Number  per  cent 

of  double 

kernels 


3.05 

.60 
7.37 
8.54 

.97 

10.29 

9.51 

29.50 

6.62 

1.88 

.032 
1.14 

.88 
2.93 


The  above  figures  are  for  hand-shelled  almonds  from  young  trees. 
It  must  be  remembered  that  the  figures  will  vary  on  older  trees  and 
also  that  the  percentage  of  kernel  to  whole  nuts  will  be  lower  for 
samples  from  commercial  shelling  plants. 

Methods  of  Classification. — Almonds  are  classified  according  to 
hardness  of  shell: 

Papershell. — Those  having  a  thin,  papery  shell  which  may  be 
broken  easily  between  the  fingers  of  one  hand. 

Softshell. — Those  which  have  a  more  or  less  spongy  or  thin  shell 
which  may  be  broken  between  the  fingers  of  two  hands. 


56 


UNIVERSITY   OF    CALIFORNIA — EXPERIMENT    STATION 


Standardshell. — Those  requiring  very  strong  pressure  of  the  hand 
or  the  use  of  a  nut-craeker  to  break.  These  may  have  a  spongy  or 
smooth  outer  shell. 

Hardshell. — Those  which  cannot  be  broken  by  hand  but  require  a 
sharp  blow  with  a  hammer  or  strong  pressure  with  a  nut-cracker  to 
crack  them. 

The  papershell  varieties  are  excellent  for  shelling,  as  they  contain 
a  large  percentage  of  kernels  which  may  easily  be  obtained  whole. 


'x 


Fig.  18. — Almond  varieties. 

The  principal  objections  are  that  birds  are  particularly  fond  of  them 
since  they  can  crack  them  easily,  and  that  the  shells  are  often  poorly 
sealed.  The  latter  fact  makes  it  difficult  to  prevent  worm  infestation 
and  the  entrance  of  sulphur  fumes  into  the  kernel  during  the  bleach- 
ing process.  As  a  result,  practically  none  of  the  papershells  are 
bleached  but  are  sold  for  shelling  purposes. 

The  softshells  are  generally  more  attractive  for  table  use  because 
the  shells  are  more  perfect  and,  in  commercial  varieties,  are  brighter 
in  color  and  more  attractive.  The  shells  are  usually  well  sealed  and 
can  be  bleached  to  give  additional  brightness  with  less  danger  of  the 
fumes  penetrating  to  the  kernel  than  in  the  case  of  the  papershells. 


Circ.  284] 


THE  ALMOND  IN   CALIFORNIA 


57 


The  standardshells  have  the  greatest  range  in  character,  thickness, 
and  hardness  of  shell.  The  percentage  of  kernel  is  too  low  to  make 
them  very  attractive  to  the  retail  trade.  Of  this  class  the  Drake  is 
probably  the  best  of  the  California  varieties.  Almond  varieties  of  all 
these  classes  are  shown  in  figures  18  and  19.  These  illustrations  show 
most  of  the  varieties  grown  to  any  extent  in  California  and  others  that 
have  attracted  much  interest  and  inquiry,  together  with  the  European 
Tarragona. 


;v>V' 


*. 


•  A 


■  mmm** 


fe-^S*^ 


Fig.  19. — Almond  varieties. 


ACKNOWLEDGMENTS 


The  writers  desire  to  express  their  appreciation  to  the  California 
Almond  Growers'  Exchange,  and  to  Mr.  M.  N.  Wood,  Pomologist, 
U.  S.  Department  of  Agriculture,  who  have  provided  certain  data  and 
given  helpful  suggestions,  and  to  acknowledge  the  help  and  sugges- 
tions received  from  Dr.  W.  L.  Howard,  who  gave  valuable  assistance 
in  the  preparation  of  the  manuscript. 


STATION  PUBLICATIONS  AVAILABLE  FOR  FRPJE  DISTRIBUTION 


BULLETINS 

No.  No. 

253.   Irrigation   and   Soil  Conditions  in  the  352. 
Sierra  Nevada  Foothills,  California. 

261.  Melaxuma    of    the    Walnut,     "Juglans  353. 

regia."  354. 

262.  Citrus  Diseases  of  Florida  and  Cuba  357. 

Compared  with  Those  of  California. 

263.  Size  Grades  for  Ripe  Olives. 

268.   Growing  and  Grafting  Olive  Seedlings.  358. 
273.   Preliminary  Report  on  Kearney  Vine- 
yard Experimental  Drain.  359. 

275.  The  Cultivation  of  Belladonna  in  Cali-  361. 

fornia. 

276.  The  Pomegranate.  362. 

277.  Sudan  Grass  363. 

278.  Grain  Sorghums. 

279.  Irrigation  of  Rice  in  California.  364. 

280.  Irrigation  of  Alfalfa  in  the  Sacramento 

Valley.  366. 

283.  The  Olive  Insects  of  California. 

285.  The  Milk  Goat  in  California.  367. 

286.  Commercial  Fertilizers. 

294.   Bean  Culture  in  California.  368. 
304.  A   Study  of  the  Effects  of  Freezes  on 

Citrus   in   California.  369. 

310.  Plum  Pollination.  370. 

312.  Mariout  Barley.  371. 

313.  Pruning  Young  Deciduous  Fruit  Trees. 

319.   Caprifigs  and  Caprification.  372. 

324.  Storage  of  Perishable  Fruit  at  Freezing 

Temperatures.  374. 

325.  Rice  Irrigation  Measurements  and  Ex- 

periments    in      Sacramento     Valley, 
1914-1919.  375. 

328.   Prune  Growing  in  California. 

331.   Phylloxera-Resistant  Stocks.  376. 

334.  Preliminary  Volume  Tables  for  Second- 

Growth  Redwood.  377. 

335.  Cocoanut   Meal    as    a    Feed   for   Dairy  379. 

Cows  and  Other  Livestock.  380. 

339.  The  Relative  Cost  of  Making  Logs  from 

Small  and  Large  Timber.  381. 

340.  Control  of  the  Pocket  Gopher  in  Cali- 

fornia. 382. 

343.  Cheese  Pests  and  Their  Control. 

344.  Cold  Storage  as  an  Aid  to  the  Market-  383. 

ing  of  Plums. 

346.  Almond  Pollination.  384. 

347.  The  Control  of  Red  Spiders  in  Decidu- 

ous Orchards. 

348.  Pruning  Young  Olive  Trees.  385. 

349.  A    Study    of     Sidedraft    and    Tractor  386. 

Hitches. 

350.  Agriculture  in  Cut-over  Redwood  Lands. 


Further  Experiments  in  Plum  Pollina- 
tion. 

Bovine  Infectious  Abortion. 

Results  of  Rice  Experiments  in   1922. 

A  Self-mixing  Dusting  Machine  for 
Applying  Dry  Insecticides  and 
Fungicides. 

Black  Measles,  Water  Berries,  and 
Related  Vine  Troubles. 

Fruit  Beverage  Investigations. 

Preliminary  Yield  Tables  for  Second 
Growth   Redwood. 

Dust  and  the  Tractor  Engine. 

The  Pruning  of  Citrus  Trees  in  Cali- 
fornia. 

Fungicidal  Dusts  for  the  Control  of 
Bunt. 

Turkish  Tobacco  Culture,  Curing  and 
Marketing. 

Methods  of  Harvesting  and  Irrigation 
in  Relation  to  Mouldy  Walnuts. 

Bacterial  Decomposition  of  Olives  dur- 
ing Pickling. 

Comparison  of  Woods  for  Butter  Boxes. 

Browning  of  Yellow  Newtown  Apples. 

The  Relative  Cost  of  Yarding  Small 
and  Large  Timber. 

The  Cost  of  Producing  Market  Milk  and 
Butterfat  on  246  California  Dairies. 

A  Survey  of  Orchard  Practices  in  the 
Citrus  Industry  of  Southern  Cali- 
fornia. 

Results  of  Rice  Experiments  at  Cor- 
tena,   1923. 

Sun-Drying  and  Dehydration  of  Wal- 
nuts. 

The  Cold  Storage  of  Pears. 

Walnut  Culture  in  California. 

Growth  of  Eucalyptus  in  California 
Plantations. 

Growing  and  Handling  Asparagus 
Crowns. 

Pumping  for  Drainage  in  the  San 
Joaquin  Valley,   California. 

Monilia  Blossom  Blight  (Brown  Rot) 
of  Apricot. 

A  Study  of  the  Relative  Values  of  Cer- 
tain Succulent  Feeds  and  Alfalfa  Meal 
as  Sourses  of  Vitamin  A  for  Poultry. 

Pollination  of  the  Sweet  Cherry. 

Pruning  Bearing  Deciduous  Fruit 
Trees. 


CIRCULARS 


No.  No. 

87.   Alfalfa.  155. 

113.    Correspondence  Courses  in  Agriculture.  157. 

117.  The    Selection    and    Cost    of    a    Small  160. 

Pumping  Plant.  161. 

127.   House  Fumigation.  164. 

129.   The  Control  of  Citrus  Insects.  165. 
136.  Melilotus    indira    as    a    Green-Manure 

Crop  for  California.  166. 

144.    Oidium  or  Powdery  Mildew  of  the  Vine.  167. 

151.  Feeding  and  Management  of  Hogs.  170. 

152.  Some  Observations  on  the  Bulk  Hand- 

ling of  Grain  in  California.  173. 
154.   Irrigation   Practice   in   Growing  Small 

Fruit  in  California.  178. 


Bovine  Tuberculosis. 

Control  of  the  Pear  Scab. 

Lettuce  Growing  in  California. 

Potatoes  in  California. 

Small  Fruit  Culture  in  California. 

Fundamentals   of   Sugar   Beet   Culture 

under  California  Conditions. 
The  County  Farm  Bureau. 
Feeding  Stuffs  of  Minor  Importance. 
Fertilizing  California  Soils  for  the  1918 

Crop. 
The    Construction    of    the    Wood-Hoop 

Silo. 
The  Packing  of  Apples  in  California. 


CIRCULARS — {Continued) 


No. 
179. 

184. 
190. 
199. 
202. 

203. 
208. 

209. 
210. 
212. 
214. 

215. 
217. 

220. 
228. 
231. 
232. 

233. 
234. 

235. 

236. 


237. 

238. 
239. 

240. 

241. 

243. 

244. 
245. 
247. 
248. 

249. 
250. 


Factors   of   Importance    in    Producing 

Milk  of  Low  Bacterial  Count. 
A  Flock  of  Sheep  on  the  Farm. 
Agriculture  Clubs  in  California. 
Onion  Growing  in  California. 
County   Organizations   for   Rural   Fire 

Control. 
Peat  as  a  Manure  Substitute. 
Summary  of  the  Annual  Reports  of  the 

Farm  Advisors  of  California. 
The  Function  of  the  Farm  Bureau. 
Suggestions  to  the  Settler  in  California. 
Salvaging  Rain-Damaged  Prunes. 
Seed  Treatment  for  the  Prevention  of 

Cereal  Smuts. 
Feeding  Dairy  Cows  in  California. 
Methods  for  Marketing  Vegetables   in 

California. 
Unfermented  Fruit  Juices. 
Vineyard  Irrigation  in  Arid  Climates. 
The  Home  Vineyard. 
Harvesting    and    Handling    California 

Cherries  for  Eastern  Shipment. 
Artificial  Incubation. 
Winter  Injury  to  Young  Walnut  Trees 

during  1921-22. 
Soil  Analysis  and  Soil  and  Plant  Inter- 
relations. 

The  Common  Hawks  and  Owls  of  Cali- 
fornia   from    the    Standpoint   of   the 

Rancher. 
Directions  for  the  Tanning  and  Dress- 

of  Furs. 
The  Apricot  in  California. 
Harvesting  and  Handling  Apricots  and 

Plums  for  Eastern  Shipment. 
Harvesting    and    Handling    Pears   for 

Eastern   Shipment. 
Harvesting  and  Handling  Peaches  for 

Eastern  Shipment. 
Marmalade  Juice  and  Jelly  Juice  from 

Citrus  Fruits. 
Central  Wire  Bracing  for  Fruit  Trees. 
Vine  Pruning  Systems. 
Colonization  and  Rural  Development. 
Some  Common  Errors  in  Vine  Pruning 

and  Their  Remedies. 
Replacing  Missing  Vines. 
Measurement  of   Irrigation   Water  on 

the  Farm. 


No. 
251. 


252. 
253. 
254. 

255. 

256. 
257. 
258. 
259. 
260. 

261. 
262. 
263. 
264. 

265. 
266. 

267. 

268. 

269. 
270. 
271. 
272. 

273. 
275. 

276. 

277. 

278. 
279. 
281. 


282. 


Recommendations  Concerning  the  Com- 
mon Diseases  and  Parasites  of 
Poultry  in  California. 

Supports  for  Vines. 

Vineyard  Plans. 

The  Use  of  Artificial  Light  to  Increase 
Winter  Egg  Production. 

Leguminous  Plants  as  Organic  Fertil- 
izer in  California  Agriculture. 

The  Control  of  Wild  Morning  Glory. 

The  Small-Seeded  Horse  Bean. 

Thinning  Deciduous  Fruits. 

Pear  By-products. 

A  Selected  List  of  References  Relating 
to  Irrigation  in  California. 

Sewing  Grain   Sacks. 

Cabbage  Growing  in  California. 

Tomato  Production  in  California. 

Preliminary  Essentials  to  Bovine  Tuber- 
culosis Control. 

Plant  Disease  and  Pest  Control. 

Analyzing  the  Citrus  Orchard  by  Means 
of  Simple  Tree  Records. 

The  Tendency  of  Tractors  to  Rise  in 
Front;  Causes  and  Remedies. 

Inexpensive  Lavor-saving  Poultry  Ap- 
pliances. 

An  Orchard  Brush  Burner. 

A  Farm  Septic  Tank. 

Brooding  Chicks  Artificially. 

California  Farm  Tenancy  and  Methods 
of  Leasing. 

Saving  the  Gophered  Citrus  Tree. 

Marketable  California  Decorative 
Greens. 

Home  Canning. 

Head,  Cane,  and  Cordon  Pruning  of 
Vines. 

Olive  Pickling  in  Mediterranean  Coun- 
tries. 

The  Preparation  and  Refining  of  Olive 
Oil  in  Southern  Europe. 

The  Results  of  a  Survey  to  Determine 
the  Cost  of  Producing  Beef  in  Cali- 
fornia. 

Prevention  of  Insect  Attack  on  Stored 
Grain. 


The  publications  listed  above  may  be  had  by  addressing 

College  of  Agriculture, 

University  of  California, 

Berkeley,  California. 


15m-4,'25 


